Loneliness and mental health challenges are increasingly prevalent among students, highlighting the urgent need for effective interventions. This study explores the role of physical activity and social engagement in combating loneliness and improving mental health, focusing specifically on community gardening and other physical activities. Using a mixed-methods design, we assess the interconnected benefits of these activities among a diverse sample of 16,000 students. Central to this investigation is the mediating role of Connectedness to Nature, which may enhance the psychological benefits of physical exercise. By fostering a sense of belonging and purpose, community gardening offers a dual benefit of promoting physical health and social interaction. Quantitative measures examine the adoption rates, perceived value, and mental health outcomes of community gardening and other activities, while qualitative insights provide depth to the understanding of students' experiences. The findings aim to illuminate pathways through which nature-oriented and socially engaging physical activities mitigate loneliness and promote mental well-being. This study contributes to evidence-based strategies for universities and communities to support students, emphasizing the integration of accessible, nature-based, and socially engaging practices in mental health interventions. By bridging physical activity, social connection, and nature, this research offers a holistic approach to improving student mental health.