To address the gaps in current knowledge, this study aimed to examine the effect of a school-based health promotion program on both physical and mental health among late school-aged children. Changes in health status were assessed using both self-report measures and physiological measures, including HRV. Also, based on previous evidence of a positive effect of nature on physical and mental health [13] [14], we included naturerelated activities for the experimental group, and tested the effect of this program.