There is a correlation between physical activity and physical development in young men your age. A recent study found that boys involved in sports of any kind (swimming, tennis, football) were taller, heavier, and leaner than their less physically active peers. They also had better bone mineral content.
Perhaps you and your friends could get your own sports group going. The study made no distinction between those who excel at sports versus those who were just out there trying! Your efforts to become more physically active can improve the health of your bones today, establishing a better reserve of bone for your future years.