If longitudinal studies can confirm the present results, it may be suggested that tailored interventions to improve mental health-related quality of life in middle-aged and older adults should use a combined strategy, focusing on increasing perceived social support for physical activity from friends or family and leisure-time physical activity. Previous study findings emphasized the importance of general social support (e.g the warmth and friendliness of the surrounding environment) [12], but the present study showed that perceiving support specifically for physical activity may also be beneficial for mental health. This positive association works both direct and indirect through increased physical activity. Findings also suggest the importance of policies to promote and improve the neighbourhood physical activity environment, neighbourhood personal safety and neighbourhood social cohesion for improving mental health-related quality of life, although the mediating effect of physical activity on these associations is rather limited. Further research is needed to clarify the underlying mechanisms explaining these relationships. Nonetheless, although the mediating effect of physical activity on the relationship between the neighbourhood social and physical environment and mental health-related quality of life was small, these results are important as broader environmental changes have the opportunity to affect large populations [64]. Consequently, small effects can still have important implications for population health.