Effects of a Healthy Lifestyle and Mental Well-Being Programme on Stress and Physical Activity among Secondary School Students: A Pre–Post Intervention Study

Mental health issues have become a significant factor affecting the development of adolescents. Upon entering adolescence, secondary school students must cope with academic demands, peer relationships and changes in lifestyle; these factors can easily lead to increased stress and affect their overall health. Existing research indicates a close link between a healthy lifestyle and a positive mental state, with physical activity considered capable of improving mood, reducing psychological strain and promoting psychological resilience. As schools are key settings in adolescents’ daily lives, they have gradually begun to implement health promotion programmes to improve students’ physical and mental well-being; however, the effectiveness of such interventions still requires further validation. This study employed a single-group pre–post design to evaluate a Healthy Lifestyle and Mental Well-Being Programme among 42 secondary school students in Malaysia. Paired-sample t-tests revealed no statistically significant changes in psychological stress (pre: M = 18.54 ± 4.14; post: M = 18.90 ± 4.77; t = -0.367, p = 0.716) or physical activity levels (pre: M = 24.51 ± 5.03; post: M = 25.63 ± 5.58; t = −0.859, p = 0.396) following the intervention. Despite the absence of statistically significant objective changes, programme feedback was consistently positive, with mean satisfaction scores ranging from 3.78 to 4.20 out of 5. These findings suggest that while short-term measurable effects were limited, the programme demonstrated strong acceptability and warrants further investigation using controlled designs with extended follow-up periods.