This structured protocol was a 10-day nature-based program with high level of nature engagement and involvement of multiple sensory processes. The program was held in lunch breaks between 12:00 noon and 2:00 p.m. Each session consisted of 30 minutes in the Eco Garden of The Education University of Hong Kong. Activities of this program included walking, ecological photography, sketching butterflies, planting vegetables, drinking herbal tea, observing birds, and taking a nap in nature. Each activity corresponded to specific sensory pathways. For example, butterfly sketching is focused on the use of visual sense, whereas drinking herbal tea involved sense of taste, smell, and touch. Trainers with master's degrees in environmental education and rich experience in guiding ecological tours provided instructions and guidance to participants during the activities. Participants were also asked to pay attention to their surroundings and focus on their five senses during participation.

Participants who were randomly assigned to the waitlist control group were instructed to spend their usual half-hour lunch break in the office for consecutive 10 weekdays. Also, the waitlist control group was told to wait for at least three months before they took part in the structured protocol of nature contact.

This structured protocol was a 10-day nature-based program with high level of nature engagement and involvement of multiple sensory processes. The program was held in lunch breaks between 12:00 noon and 2:00 p.m. Each session consisted of 30 minutes in the Eco Garden of The Education University of Hong Kong. Activities of this program included walking, ecological photography, sketching butterflies, planting vegetables, drinking herbal tea, observing birds, and taking a nap in nature. Each activity corresponded to specific sensory pathways. For example, butterfly sketching is focused on the use of visual sense, whereas drinking herbal tea involved sense of taste, smell, and touch. Trainers with master's degrees in environmental education and rich experience in guiding ecological tours provided instructions and guidance to participants during the activities. Participants were also asked to pay attention to their surroundings and focus on their five senses during participation.

The Chinese version of the 7-item Generalized Anxiety Disorder (GAD-7) was used to measure anxiety symptoms at all time points. Participants rated each item on a 4-point scale ranging from 0 (not at all) to 3 (nearly every day) based on their experience in the past two weeks. Higher scores indicated greater severity of anxiety symptoms (range = 0-21).

Depressive symptoms were measured using the Chinese version of the Patient Health Questionnaire-9 (PHQ-9) at T1, T2, and T3, respectively. Participants rated each item on a 4-point scale as in GAD-7. Higher scores indicate the greatest severity of the depressive symptoms (range 0-27).

Perceived stress was assessed at all time points using the Chinese version of the 10-item Perceived Stress Scale (PSS-10). Participants reported their subjective stress in the past two weeks on a 5-point scale (0 = never, 4 = very often). Total scores ranged from 0 to 40, with higher scores indicating higher levels of perceived stress.

The WHO-Five Well-being Index (WHO-5) consisted of five positively worded items. Participants were asked to report the presence of the five positive mental states in the past 2 weeks on a 6-point scale ranging from 0 (at no time) to 5 (all of the time).