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Forest Therapy Alone or with a Guide: Is There a Difference between Self-Guided Forest Therapy and Guided Forest Therapy Programs?

International Journal of

Environmental Research

and Public Health

Article

Forest Therapy Alone or with a Guide: Is There a Difference

between Self-Guided Forest Therapy and Guided Forest

Therapy Programs?

Jin-Gun Kim 1 and Won-Sop Shin 2,*

1 Korea Forest Therapy Forum Incorporated Association, Cheongju 28644, Korea; K64804171@gmail.com

2 Department of Forest Sciences, Chungbuk National University, Cheongju 28644, Korea

* Correspondence: shinwon@chungbuk.ac.kr; Tel.: +82-43-261-2536

Citation: Kim, J.-G.; Shin, W.-S.

Forest Therapy Alone or with a

Guide: Is There a Difference between

Self-Guided Forest Therapy and

Guided Forest Therapy Programs?

Int. J. Environ. Res. Public Health 2021,

18, 6957. https://doi.org/10.3390/

ijerph18136957

Academic Editor: Paul B. Tchounwou

Abstract: There are generally two types of forest therapy. One is to walk or view the forest alone

without a guide, and the other is to be accompanied by a guide. This study aimed to investigate the

healing factors and health beneﬁts of self-guided forest therapy and guided forest therapy programs

and examine the differences in characteristics between interventions. Thirty-seven undergraduate

students participated in a randomized experiment (19 in the self-guided forest therapy and 18 in

the guided forest therapy program). Data were collected from 111 self-reported essays after each

intervention (three essays per person). Results revealed that the forest healing factors contained

four categories in common: auditory element, visual element, tactile element, and olfaction element.

Forest therapy’s health beneﬁts included ﬁve categories in common: change of mind and body,

introspection, change of emotion, cognitive change, and social interaction. Among the typical

differences, the self-guided forest therapy group mentioned more keywords related to introspection

than the guided forest therapy program group. On the other hand, the guided forest therapy program

group mentioned more keywords associated with the change of emotion and social interaction than

the self-guided forest therapy. Our ﬁndings show that self-guided forest therapy provides an

opportunity for self-reﬂection to focus on and think about one’s inner self. On the other hand, guided

forest therapy programs provide positive emotional changes and promoting social bonds through

interaction with others. Therefore, because the effects that can be obtained vary depending on the

type of forest therapy, participants can utilize forest healing to suit the desired outcomes.

Keywords: self-guided forest therapy; guided forest therapy program; healing factor; health beneﬁt

Received: 14 May 2021

Accepted: 28 June 2021

Published: 29 June 2021

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1. Introduction

The world has become an urban society, with over half the world’s populations living

in urbanized areas. Urbanization, deﬁned as the relative increase of the urban population

as a proportion of the total population [1], is a demographic movement and includes

social, economic, and psychological changes [2]. Historically, urbanization was related to

positive economic development and provided many opportunities such as education and

good infrastructure [3], but overexposure to stress caused mental health problems [4,5].

Urbanization negatively affects mental health by inﬂuencing increased stressors and factors

such as overcrowded and polluted environments, high noise levels, higher crime rates,

reduced social support, and lack of calming scenery [6]. Therefore, it is crucial to ﬁnd ways

of promoting mental health recovery in daily life.

Connecting with forests has been increasingly recognized as an effective method of

dealing with mental problems [7,8]. The term “forest bathing,” derived from Japan, is

deﬁned as being in a forest environment to restore balance psychologically and physiolog-

ically and absorb its atmosphere [9]. In later years, the term “forest bathing” developed

into “forest therapy,” which is the medically proven health effects of exposure to forest

environment [10]. The Korea Forest Service (KFS) has legitimized the concept of forest

Int. J. Environ. Res. Public Health 2021, 18, 6957. https://doi.org/10.3390/ijerph18136957

https://www.mdpi.com/journal/ijerph

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therapy and deﬁned forest therapy as “immune-strengthening of the human body and

health-promoting activities by utilizing various elements of nature, such as scent and

landscape [11].” Based on the empirical research evidence, the Korea Forest Service (KFS)

facilitated forest therapy to utilize forests for enhancing people’s health and quality of life.

Many studies demonstrated forest environments promote humans’ mental and phys-

ical health in many ways. For example, spending time in a forest environment reduces

pulse rate and blood pressure [12,13], sympathetic nervous activity [14,15], and levels of

salivary cortisol [16,17], and increases parasympathetic nervous activity [18,19] and NK

cell activity, which relate to the immune system [20,21]. In addition, many studies have

shown the beneﬁcial effects on mental health of being in the forest. Those studies indicated

that being in the forest can reduce negative emotion [22,23], depression [24], anxiety [25],

and stress [26], and increase positive emotion [22–24] and self-esteem [27].

There are generally two types of forest therapy. One is to walk or view the forest alone

without a guide and the other is to be accompanied by a guide. Namely, when people visit

the forest to improve their health, people participate in forest walking or viewing forests

individually or participating in a forest therapy program, guided by the therapist with a

license. A forest therapy program is a set of structured activities and cognitive-behavioral

therapy-based interventions using various elements of the forest environment to mitigate

stress and to promote health [28]. Many previous studies have reported the effects of the

two types of activities in forest therapy.

For individual visits to forests without a guide, numerous studies have demonstrated

the effects of walking or viewing the forest alone in relieving stress levels and inducing

psychological relaxation [14,22,29,30]. For example, Park et al. [22] showed that walking

and viewing forests improved emotional state, leading to psychological relaxation. Song

et al. [30] also reported that participants who walk in a forest increase parasympathetic

nervous activity and decrease sympathetic nervous activity and heart rate compared to

walking in a city environment. In addition, those who walked in a forest improved positive

emotions such as vigor and reduced the anxiety dimension of the STAI and negative

emotions such as tension/anxiety, depression/dejection, anger/hostility, fatigue, and

confusion. Research has also shown that exposure to nature, such as forests, improves

cognitive tasks requiring direct attention. For example, Tennesen and Cimprich [31]

reported that students who could see the natural environment through dormitory windows

performed better on tasks requiring concentration than those who did not. A similar study

by Taylor et al. [32] showed that children who see urban forests around apartments perform

better in memory, impulse control, selective attention, and concentration. Berto [33] also

reported that participants who looked at pictures of the natural environment had more

sustained attention than those who looked at images of the urban environment. Similarly,

walking in a natural environment has shown advantages in language work memory and

cognitive control relative to walking in an urban environment [34–36].

Previous studies also showed that being in the forest without a guide can relax the

body and mind and provides an opportunity to look back on oneself. For example, Sonntag

et al. [37] reported people diagnosed with exhaustion disorder who spent two hours

alone in the forest increased happiness and were more relaxed, harmonious, alert, and

clear-headed compared to before. Furthermore, those who participated also reported

that they began to take charge of their lives after a while, and that they began to plan to

change their lives after a very long time. Korperla [38] and Hammitt [39] also showed that

solitude in natural places could regulate negative moods. Being in a restorative natural

environment that deviates from everyday life can provide an opportunity to look at life in a

different context, connecting concepts that could not have been created before. The privacy

available in the forest offers a unique setting to utilize self-reﬂection. Self-reﬂection has been

described as involving “active, persistent, and careful consideration” [40]. Boud et al. [41]

describe it as “those activities individuals engage in to explore experiences.” With the

many distractions experienced in modern life, reﬂection, self-awareness, and integration

are very important. The self-reﬂection chance offered by nature might be maximized when

Int. J. Environ. Res. Public Health 2021, 18, 6957

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spending time in the forest autonomically rather than controlled by guides. It could mean

that being self-guided in a forest setting might provide an opportunity to think about the

current situation and allow more positive thinking. During this process, the environmental

elements of forests, which can be represented by the scenery, smell, and sound of the forest,

can stimulate the ﬁve senses of humans to sympathize with natural environments in the

forest.

Many previous studies have reported that the guided forest therapy programs can

have a substantial physiological and psychological response. For example, forest therapy

program provided a decrease in pulse rate [42], blood pressure [42,43], and cortisol [44],

reduced negative emotion, and improved positive emotion [45,46]. Furthermore, many

studies have investigated elderly individuals and adults at risk of stress and lifestyle-

related diseases such as high blood pressure, diabetes, and depression. For example,

Ochiai et al. [47] conducted a forest therapy program for middle-aged males with high

normal blood pressure. The results showed that participants’ systolic and diastolic blood

pressure, urinary adrenaline, and serum cortisol were signiﬁcantly reduced after forest

therapy. Participant’s negative emotion scores such as tension/anxiety, confusion, and

anger/hostility, and total mood disturbance scores were reduced. Song et al. [48] reported

that systolic and diastolic blood pressure decreased during the forest therapy program,

and these decreases were maintained for ﬁve days. Shin et al. [49] also reported that the

two-day forest therapy program provided signiﬁcantly positive changes in workers’ job

stress and moods. In addition, the effects of a forest therapy program for people who

have mental health problems have been investigated. Bielinis et al. [50] conducted a forest

therapy program for people with post-traumatic stress disorder or experiencing stress.

The results showed that in people with psychotic disorders, the forest therapy program

increases the vigor trait. In contrast, in patients with affective disorders, the forest therapy

program was more effective in improving confusion and depression/dejection traits. Woo

et al. [51] also found that patients with a major depressive disorder showed more signiﬁcant

improvement in depression and quality of life after the forest therapy program. Hong

et al. [52] reported that psychiatric outpatients who participated in a three-day forest

therapy program reduced depression, anxiety, and anger, and improved quality of life

compared to before.

The forest therapy program is also helpful in social health. Especially for children,

previous studies showed that forest therapy programs could improve sociality [53,54], so-

cial competence [55,56], and social development [57,58], and reduce problem behavior [59].

For example, Jang et al. [58] reported that an after-school forest therapy program for infant

participants effectively improved pro-social behavior and expression efﬁciency. In addition,

Kim and Kang [57] showed that cooperative play in the forest improves young children’s

social skills and happiness. Choi et al. [55] also reported that children who played in

the forest enhanced their sense of social competence and happiness relative to playing in

the classroom. Lee et al. [60] reported that middle-aged women who participated in the

urban forest therapy program acquired knowledge about nature and forming emotional

bonds with one another. According to Rogers [61], the process of psychological change

formed by building social relationships in forest environments was similar to developing

rapport. Moreover, the participants began to share their negative feelings after positive

feelings developed through mutual understanding and regard. Overall, ﬁndings seem to

suggest that a guided forest therapy program brings about positive impacts on individuals’

psychological and physiological functioning as well as social skill. Guided forest therapy

programs are led by trained forest therapy guides and involve various physical activities

that would not be possible to engage in alone, although slight variation may exist between

programs. Guided forest therapy programs may share a variety of emotions and help social

interactions by experiencing various activities with participants under the guidance of

therapists.

However, few studies have discussed and investigated the difference between being

in the forest alone and guided forest therapy programs. Staats and Hartig [61] investigated

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social context inﬂuences (alone or in the company of a friend) and psychological restoration

on preferences for natural and urban environments. It was found that the company of a

friend created a feeling of safety that could enable restoration. However, when security

is ensured, they found walking alone enhanced more restoration than being in company.

Igawahara et al. [62] investigated participants’ physiological and psychological effects

in the forest therapy and walk-alone program. The results showed that subjects who

participated in the forest therapy program found it more therapeutic and relaxing than

those who participated in the walk-alone program. Lim et al. [63] reported that comparing

the guided and unguided conditions, there were no signiﬁcant differences in the change in

nature connectedness, mood, or heart rate.

Even though a few studies have examined the differences between guided forest

therapy program and self-guided forest therapy, it remains unclear whether and how

guided or unguided forest therapy could contribute to participants’ health. There is still

a general lack of research on this area. Therefore, this study aimed to investigate the

healing factors and health beneﬁts of self-guided forest therapy and guided forest therapy

programs and examine the differences in characteristics between interventions.

The following research hypotheses were formulated in the study:

1. The self-guided forest therapy group will mention more varied forest healing factors

than those who participated in the guided forest therapy program.

2. The self-guided forest therapy group will mention reﬂecting on oneself more than

those who participated in the guided forest therapy program.

3. The guided forest therapy program group will mention more varied emotional

changes than those who participated in the self-guided forest therapy.

4. The guided forest therapy program group will mention more social interaction than

those who participated in the self-guided forest therapy.

2. Materials and Methods

2.1. Participants

Thirty-seven undergraduate students of Chungbuk National University (23 males,

14 females) participated in this study, and their mean age was 21.4 ± 1.3 years. Participants

were recruited by posting notices throughout the university building to recruit volunteers.

No incentives were provided to the volunteers. The inclusion criteria for recruiting the

participants who were eligible for the study were: (1) no diagnosis of reaction to severe

stress and/or a depressive episode; and (2) could not be suffering from any drug or

alcohol abuse. The participants were randomly assigned into two groups (i.e., 19 in the

self-guided forest therapy group and 18 in the guided forest therapy program group). The

experiment was conducted during the 2nd semester of 2019 (September–November). A

total of eight sessions of self-guided forest therapy and guided forest therapy program

were performed. Before starting the experiments, we explained the aims and procedures

of the study to the participants and obtained a voluntarily signed agreement. This study

was approved by the Institutional Review Board of Chungbuk National University (IRB

number: CBNU-201910-SB-945-01).

2.2. Experimental Sites

The ﬁeld experiment site was conducted in the Chungbuk National University campus

forest in Korea. The size of the campus forest is about 315,000 square meters. The campus

forest mainly contains metasequoia (Metasequoia glyptostroboides), cypress (Chamaecyparis

pisifera), and mixed forest species (pitch pine, oak, chestnut), and their ages range from 40

to 90 years. Therefore, the study area was suitable for conducting forest therapy activities

regarding accessibility, distribution of various vegetation, and gentle slope. During the

eight sessions in the experiment, the weather was pleasant and not raining, with a mean

temperature of 16.2 ◦C ± 1.3 ◦C.

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2.3. Experimental Design

2.3.1. Guided Forest Therapy Program

The guided forest therapy program was provided from September to November of

2019 and consisted of one hour and a half per week for eight weeks. A trained forest

therapist delivered each session. The purpose of the guided forest therapy program was to

reduce stress and improve self-esteem and happiness for participants. During the eight

sessions of the program, participants engaged in each of the eight sessions together. They

performed various activities, such as familiar with the forest, clapping exercises, forest folk

dance, forest orienteering (using natural objects to solve group mission), forest walking,

photo healing (taking pictures of nature and story-telling), talking to nature, and a rope

game (see Table 1). The forest therapy activities were developed in consultation with

researchers in forest therapy/forest recreation and forest therapists.

Table 1. Themes and activities of the guided forest therapy program.

Session

Themes

Activities

• Ice breaking introduction; familiarity with

forest; lecture on stress management

Rapport building

• Clapping exercise; forest folk dance

• Forest orienteering (using natural objects to

solve group mission); physical stimulation

for relaxation

Stress reduction

• Group gaming activities using natural

objects (drawing natural objects, hit the

target with an acorn)

Improvement of sense of

• Forest exercise (forest walking, stretching)

belonging and self-esteem

• Barefoot walking in forest; talking to nature

• Natural object ﬁve senses game; photo

healing (taking pictures of nature and

Cooperation and trust

story-telling)

• Forest band exercise; rope game

2.3.2. Self-Guided Forest Therapy

The participants were instructed to perform forest activities for eight sessions (one

hour-long session per week). We designed the forest activities road to allow participants to

perform forest activities voluntarily without guidance by therapists. The forest activities

interventions were provided from September to November of 2019. During the eight

sessions of the intervention, participants engaged in each of the eight sessions together.

They were asked to walk the well-designated route in the campus forest, visit speciﬁc

locations where explained panels on forest activities were installed, and return to the

starting point at an appointed time. The length of the route was 1.7 km long and was

a loop trail. The self-guided forest therapy activities were designed and distributed for

the same purpose as the forest therapy program described earlier. The self-guided forest

therapy activities were picked up based on consultation from experts in the forest therapy

ﬁeld, including researchers and practitioners. Accordingly, ﬁve forest activities were

selected to apply as the self-guided forest therapy activities: stretching, respiration, walking,

meditation, and exercise.

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2.4. Data Analysis

2.4.1. Data Collection

The analysis data of this study were self-reported essays written by the subjects after the

eight-session guided forest therapy program and self-guided forest therapy activities. The

topics of essays used in this study were related to health benefits or changes that they felt

after forest therapy. The text format was free prose which was within one page of A4 sheets

in length. Participants were asked to write the essay on the day each session ended. Each

participant was asked to submit three essays during the eight sessions. Essays were collected

three times after completing one to three sessions, four to six sessions, and seven to eight

sessions. As a result, 111 essays were analyzed, with 57 essays submitted by 19 self-guided

forest therapy groups and 54 essays submitted by 18 guided forest therapy groups.

2.4.2. Qualitative Data Analysis

The collected data were analyzed using NVivo 12.0 to add reliability to the analysis of

data through transcription, coding, and analysis, and analysis of the discovery contents

of the topic presented by Kim [64]. The NVivo 12.0 qualitative data analysis software

is a tool created for social science mixed-method research that is well suited for coding

and analyzing qualitative data. For data analysis, experience essays were converted

into text documents, and the text data stored in NVivo 12.0 was repeatedly read. Open

coding was conducted to ﬁnd an inﬂuential group of words in the data and assign code

names, then reclassify them by subject. Subsequently, in-depth coding was performed

to reduce the amount of coding and to clarify its meaning. The research paradigm was

based on the post positivism [65] as it enabled us to focus on the practical application

of our research using data collection and the analytic approach best suited to testing

our research hypotheses. This approach was underpinned by ontological critical realism

and epistemological constructionism [66]. The research method was based on content

analysis, which as a research method is a systematic and objective means of describing

and quantifying phenomena [67–69]. To increase the reliability of the study, a triangulation

technique was conducted. In addition, two experts in forest recreation and forest therapy

and analyzed the essays to expand the scope of the data. The analysis was carried out in

four stages of open coding with forest therapy researchers. The two authors (J.G., W.S.)

read a sample of transcripts, continuously compared data, codes, and categories during

the coding process, and discussed the emerging themes until they reached agreement. The

sequence of analysis was as follows. First, the overall feeling and perception of forest

therapy activities were derived by repeatedly reading the data. Second, using line-by-line

analysis, each sentence was read line-by-line. All sentences containing words or contents

related to forest healing factors and health beneﬁts were coded in each case. The written

essays were initially sorted into codes based on participants’ language; code names were

developed to closely reﬂect the particular wording used by participants and were based

on the most frequently mentioned words/phrases. When possible, forest healing factors

related codes were phrased as nouns (e.g., bird sounds rather than listen to bird sounds),

highlighting the elements of the forest environments that might bring a person to the

health beneﬁts. In addition, health beneﬁts-related codes were phrased, when possible, as

descriptive statements to keep with the way participants used language to describe their

experience during forest therapy activities. For example, health beneﬁts related to positive

feelings were coded as “positive feelings were improved” rather than “positive feelings”.

Third, focusing on recurring themes of forest healing factors and health beneﬁts, concepts

were derived by similar grouping themes. Codes were clustered into themes. Each theme

was found according to the forest healing factors and health beneﬁts. Themes were derived

from participants’ language (e.g., most frequently mentioned word/phrase within a cluster

of codes) and ﬁndings from previous studies [70].

Therefore, overall, forest healing factors were restructured into four categories (audi-

tory, tactile, visual, olfactory) and health beneﬁts into ﬁve categories (change of mind and

body, change of emotion, social interaction, cognitive change, and introspection).

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2.4.3. Quantitative Data Analysis

The analysis of this study was to quantify forest healing factors and health beneﬁts de-

rived through qualitative analysis of essays submitted after the interventions. Accordingly,

quantitative data analysis was conducted for quantitative comparison between groups

according to the frequency of words related to forest healing factors and health beneﬁts.

The statistical analyses were performed using SPSS 18.0 Windows (SPSS, Chicago, IL,

USA). Pearson’s Chi-squared test of independence was used to determine the difference

between forest healing factors and health beneﬁts derived after experiencing self-guided

forest therapy and guided forest therapy programs. All statistical tests used a p-value <

0.05 as the signiﬁcance level.

3. Results

3.1. Quantitative Comparison of Forest Healing Factors in Self-Guided Forest Therapy and Guided

Forest Therapy Program

The types of forest healing factors derived from open coding in this study were shown

in 4 categories and 17 keywords: auditory elements (birds, wind sounds, fallen leaves, bug,

etc.), visual elements (natural colors, vegetation, sky, landscape, fruit, etc.), and olfactory

elements (fresh air, soil, phytoncide, etc.).

The results of the χ2 test conducted to see whether there was a signiﬁcant association

in the type of forest healing factors according to the groups are presented in Table 2. As

shown in Table 2, self-guided forest therapy was signiﬁcantly associated with the auditory

element as forest healing factors (χ2 = 8.977, p < 0.01). However, no other forest healing

factors were associated with this type of forest therapy activities. These results show that in

the self-guided forest therapy groups, auditory elements such as “bird sound” and “sound

of stepping on fallen leaves” acted as healing factors for participants. These auditory

elements might give comfort and pleasure to participants in a self-guided forest therapy

group.

Table 2. Written response category and frequencies on forest healing factors by type of forest therapy activity.

Category

SGFT (n = 57) GFTP (n = 54)

χ2

Cramer’s V

Effect Size

Change of mind and body

77.2 46

85.2

1.155

0.283

Introspection

63.2 20

37.0

7.569

0.006 **

Change of emotion

38.6 37

68.5

9.971

0.002 **

Cognitive change

36.8 22

40.7

0.178

0.673

Social interaction

8.8

48.1

21.360 <0.001 ***

0.102

0.261

0.300

0.040

0.439

Weak

Moderate

Negligible

Relatively strong

Notes: SGFT (‘Self-guided’ forest therapy) and GFTP (guided forest therapy program). *** p < 0.001, ** p < 0.01.

These results show that self-guided forest therapy provided an opportunity to re-

ﬂect on oneself and organize ideas through dialogue with the inside. Examples of the

introspection of participants in self-guided forest therapy group are as follows.

“The best thing about running a self-guided forest therapy program was that I could

organize my thoughts. I like to answer the question thrown. What about you, not the

kind of question that solves the problem? A question of feeling. I could get one step closer

to myself in the woods and trees, and I think it was precious. At the time, I focused solely

on myself.” (SGFT participant 4)

“During the self-guided forest therapy program, I was able to think deeply about what

I thought, what I wanted, and what I lacked because I could lean on trees in the forest

without any pressure or burden.” (SGFT Participant 16)

On the other hand, participants in the guided forest therapy program group experienced

positive emotions due to the beauty of the forest and various elements in the forest and

showed that negative emotions such as anxiety and tension were resolved. In particu-

lar, participants who experienced the guided forest therapy program mentioned many

keywords related to fun/joy/laughter among positive emotions.

The following are examples of the fun/joy/laughter of participants in the guided

forest therapy program group.

“I don’t think I’ve ever laughed and focused like this lately. I laughed and enjoyed many

activities with forest therapy instructors and friends, and naturally, negative feelings

disappeared. Now I wait for the most time of the week for the guided forest therapy

program. However, not just me but also friends who participate in the program wait for

the forest therapy program the most.” (GFTP Participant 10)

“It is a good time because it brings peace and stability through the forest therapy program,

and it is nothing but laughter and happiness. I don’t laugh much, but I feel relaxed, so

I laugh a lot these days even though it’s nothing special. It’s also because of this time.”

(GFTP Participant 14)

“I haven’t laughed without thinking recently, but at this time, I laughed without thinking

and felt refreshed.” (GFTP Participant 11)

In addition, the guided forest therapy program provided participants with social effects

such as building intimacy and improving interpersonal relationships. Most participants

noted that forming social relationships with other participants was one of the most valuable

guided forest therapy programs.

The following are examples of participants who experienced the guided forest therapy

program.

“Through hand massage activities, I felt better because the smell of oil was good, and I

had a chance to touch my friend’s hand, so I learned how my friend’s hand looked and felt,

and I felt more intimate with my friend.” (GFTP Participant 7)

“In the ﬁrst week, it was an interview activity to recognize each other in the forest. I’ve

only been acquainted with my classmates, and I haven’t been so close. This activity

allowed me to get closer to my partner.” (GFTP Participant 14)

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“I covered my eyes with an eye patch and played a game of running around the lawn

with only the leader and team members. As I closed my eyes, the team members were the

only ones to rely on. I was scared, but I relied on it that much, and I gained intimacy.”

(GFTP Participant 15)

4. Discussion

This study provides empirical support for the difference between being in the forest

alone and the guided forest therapy program. These results revealed similarities and

differences between forest healing factors and health beneﬁts that acted on the self-guided

forest therapy and guided forest therapy programs. This study found that forest healing

factors commonly had four categories: auditory, visual, tactile, and olfactory. In addition,

this study found that the health beneﬁts of forest therapy commonly had ﬁve categories:

change of mind and body, introspection, change of emotion, cognitive change, and social

interaction.

4.1. Self-Guided Forest Therapy

This study revealed that the self-guided forest therapy group signiﬁcantly mentioned

more auditory elements than the guided forest therapy program group. In particular, the

self-guided forest therapy group often mentioned the sound of birds and stepping on fallen

leaves. Therefore, it is thought that subjects who participated in the self-guided forest

therapy group experienced healing factors through auditory elements, such as the sound

of birds and stepping on fallen leaves.

The results of this study are consistent with previous ﬁndings investigating preference

for natural sounds [71,72] and psychological responses [73,74]. Previous studies have

reported that while artiﬁcial sounds are considered unpleasant, forest sounds like bird

sounds are perceived as pleasant [75–77]. For example, Liu et al. [72] reported that park

users prefer natural sounds to artiﬁcial sounds. Zhang [73] showed that natural sounds

positively affected the recovery of individual attention, while artiﬁcial sounds inhibited

the recovery of individuals. A similar study by Zhang et al. [74] reported that natural

sounds such as bird sounds and water sounds positively affected the recovery of individual

attention. Self-guided forest therapy is thought to have been used for its healing factors,

such as birds and fallen leaves, because participants can quietly contemplate by doing

forest healing on their own and listen thoroughly to the sounds of nature around them.

This study revealed that the self-guided forest therapy group signiﬁcantly mentioned

introspection more than the guided forest therapy program group. Nature, such as in

a forest, provides an opportunity for self-reﬂection. Those results provide supporting

evidence for the attention restoration theory. Attention restoration theory (ART) argues

that it could be helpful because there are aesthetic advantages to nature, such as forests, and

suggests that spending time in nature gives individuals a chance to reﬂect on themselves

and time to think about unresolved issues [78–80]. Hendee and Barown [81] also reported

that forest experience provides an opportunity to evaluate individual qualities as a ﬁrst

step toward personal growth and increases awareness of individuals.

This study indicates that being alone in nature, such as a forest, can only help immerse

oneself in it. Kaplan [82] reported that being alone in the forest might give people a chance

to meditate on who they were, who they wanted to be, and realize what was important

to them. In a further study, Kaplan and Kaplan [78] reported that the forest’s attention

recovery phase went through four stages. The ﬁrst step was to organize your thoughts in

your mind; the second was to regain your attention; the third was to reduce distractions

in the mind, paying attention to an idea in silence. The ﬁnal step was to have a chance

to recover attention and have a positive change of mind through the process of setting

priorities and possibilities of life, actions, and goals, including reﬂection on one’s life.

Oh et al. [70] revealed a six-step psychological mechanism that causes emotional and

cognitive changes in nature-based healing processes. It reported that participants could

focus entirely on themselves and look into their emotions and thoughts when they have a

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deep interaction with nature. By communicating with oneself in nature, one can realize

the cause of problems and determine the change, which is reported to occur mainly in

tranquility when alone in nature. In addition, self-guided forest therapy is thought to create

an experience of immersion by conducting activities freely on one’s own. For example,

Mannel et al. [83] conducted a study of whether higher immersion levels were associated

with freely selected behavior. The result showed that free-selected intrinsic motivation

behavior caused positive effects such as more frequent immersion experiences, low tension,

and high concentration. Therefore, the results of this study suggest that subjects who

participated in the self-guided forest therapy had the opportunity to focus more on their

thoughts and organize their thoughts, not on the outside.

4.2. Guided Forest Therapy Program

The results of this study revealed that the guided forest therapy program frequently

mentioned positive emotions such as fun/joy/laughter, improvement of mood state, happi-

ness, sense of accomplishment, and negative emotions such as reduced anxiety and reduced

tension. These ﬁndings are consistent with studies suggesting that forest therapy programs

improve mood states and reduce anxiety and tension [42,45,46]. In particular, there have

been many mentions of positive emotions among changes in emotions, which can be a

decisive factor in the relationship between happiness and positive life outcomes [84], de-

pending on the cognitive model of coping [85]. Positive emotions can help individuals relax

psychologically and restore their stress-deprived resources [86]. Positive emotions can also

facilitate thinking and creativity to help solve daily life problems more ﬂexibly [87].

In the study results, participants in the guided forest therapy program mentioned a

lot of fun/joy/laughter among positive emotions. These results were judged to impact

the guided forest therapy program’s characteristics and activities content. The guided

forest therapy program consists of activities in which participants can experience forest

therapy and interact with each other. According to Reis et al. [88], the pleasure experienced

when interacting with others, especially friends, has a positive effect (in terms of fun)

over fun alone. Therefore, interaction with people provides social signals of joy and

pleasure, strengthening individuals’ emotional experience dynamically [89–91]. Moreover,

it is thought that fun/joy/laughter was mentioned during guided forest therapy program

activities because of play activities with natural objects such as the forest fork dance, natural

ﬁve-sense game, and forest orienting.

Many of the types of beneﬁts mentioned in the guided forest therapy program group

were social interactions such as intimacy formation and improvement of interpersonal

relations. The results of this study are consistent with previous ﬁndings on the social

effects of forest therapy programs. For example, Cho et al. [53] reported that a two

nights and three-day forest experience program improved low-income children’s sociality.

Oh et al. [92] also reported that the forest therapy program enhances youth capabilities,

including interpersonal skills. In addition, Jeoun et al. [93] reported that a six-session forest

experience program positively affected interpersonal relations for maladjusted soldiers.

Hendee and Barown [81] reported that collective forest experiences could provide social

interaction and improve ties. The more individuals share their inner world and feelings

with others, the more cohesive the group becomes, the more open individuals begin to be to

each other [94]. The process of psychological change caused by building social relationships

in the forest environment was similar to developing positive emotions through mutual

understanding and consideration [60]. These results can be provided as evidence to conﬁrm

the positive impact of participating in forest therapy programs on social interactions.

Therefore, this study suggests that the guided forest therapy program allows participants

to feel positive emotions inside and expect social beneﬁts through interactions between

participants as they encounter various activities using the forest environment under the

guidance of a forest therapist.

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4.3. Limitations

The study had several limitations. Firstly, the participants for this study were limited

to healthy university students in their 20s. To generalize the ﬁndings, further studies are

needed using different groups of the population with other socio-demographic character-

istics. Secondly, this study was based on self-reported essays written after forest therapy

activities. Further studies are needed to compare the physiological and psychological

effects of self-guided forest therapy and guided forest therapy programs using objective

evaluation tools. Third, inter-rater reliability was not calculated to evaluate our coding

scheme and some comments can be interpreted differently. Fourth, this study was not

considered in the context of the fundamental differences between self-guided forest ther-

apy and guided forest therapy program. For example, the guided forest therapy activities

included various physical activities that would not have been possible to engage in alone.

However, self-guided forest therapy activities consisted of activities that can be easily done

alone. Further study is needed to analyze the effects of self-guided forest therapy and

guided forest therapy by equating the contents of the program. Fifth, this study does not

include a control group performing activities in a non-forest environment. Further study

could also involve a better-controlled experiment using non-forest-related social activities

for comparison. This study contributed to understanding differences in characteristics in

self-guided forest therapy and guided forest therapy programs despite these limitations.

5. Conclusions

This study revealed the forest healing factors and health beneﬁts that acted through

self-reported essay analysis of participants in self-guided forest therapy and guided forest

therapy programs. The results showed that the forest healing factors were divided into

four categories in common: auditory, visual, tactile, and olfactory. The health beneﬁts of

forest therapy were divided into ﬁve categories: change of mind and body, introspection,

change of emotion, cognitive change, and social interaction. As a characteristic of each

activity, self-guided forest therapy provides an opportunity for self-reﬂection to focus

on and think about one’s inner self. On the other hand, guided forest therapy programs

have been shown to be effective in providing participants with positive emotional changes

and promoting social bonds through interaction with others. These ﬁndings can provide

customized forest therapy activities centered on users. Since forest healing activities can be

selected according to speciﬁc groups and speciﬁc purposes, it presents the possibility of

utilizing forests in various ways to promote health.

Author Contributions: J.-G.K. performed data acquisition, statistical analysis, interpretation of the

results, and manuscript preparation. W.-S.S. had an important a role in the overall performance of

this research, particularly the experimental design and research idea. Both authors have read and

agreed to the published version of the manuscript.

Funding: This research received no external funding.

Institutional Review Board Statement: This study was approved by the Institutional Review Board

of Chungbuk National University (IRB number: CBNU-201910-SB-945-01).

Informed Consent Statement: Informed consent was obtained from all subjects involved in the

study.

Data Availability Statement: The data presented in this study are available on request from the

corresponding author. The data are not publicly available due to privacy.

Acknowledgments: We thank the forest healing lab members of Chungbuk National University for

their help. We also gratefully thank forest therapists for their valuable guidance.

Conﬂicts of Interest: The authors declare no conﬂict of interest.

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