The positive impact of physical activity and family support on the physical and mental well-being of children and adolescents is well established. This study aims to explore the relationship between physical activity levels, body composition, symptoms of depression, anxiety, and stress, nutritional habits, mindfulness, family relationships, and the integration of cross-curricular content associated with physical education that can influence the improvement of these variables in Spanish secondary school students. A sample of 54 secondary school students in the third and fourth years (34 males and 20 females, mean age = 14.98 ± 0.62 years) participated in a 10-session intervention over five months. Participants were divided into two groups: a control group (CG; n=30) and an Experimental Group (EG; n=24). The study assessed body composition, sociodemographic characteristics, perceived family support (APGAR), adherence to the Mediterranean diet (KIDMED), levels of physical activity (IPAQ and APALQ), mindfulness (MAAS), mindful eating (MEQ) and levels of depression, stress, and anxiety (DASS-21). The results did not reveal significant effects of the 10-session intervention, based on cross-curricular competencies within a physical education class, on emotional health, eating habits, or physical activity levels among the adolescents studied. However, correlational analyses indicated that perceived family support was positively correlated with student mindfulness levels (r=0.462; p<0.01), suggesting a greater connection to reality and lower levels of depression, stress, and anxiety (r=-0.573; p<0.01). Additionally, family socioeconomic status was significantly associated with perceived family support (r=0.277; p<0.05). Physical activity habits were linked to healthier eating habits (r=0.404; p ≤ 0.01), which in turn were related to better body composition (r=-0.277; p ≥ 0.05). These findings suggest that future intervention studies aimed at improving psychoemotional health, physical activity levels, and body composition in adolescents should incorporate a focus on the family unit. © JPES.