I think teenagers can use short time efficiently-for example; playing basketball, football, baseball whatever during lunch time or running or jogging on the way to school or house. They might be able to meet friends outside during weekend and they can play together. They should not stay in house and play games and watch TV without having dermal-synthesis-getting vitamin D. Not just making them look unhealthy, it will actually make them unhealthy. Being non-balanced person during teenage time might affect on them later too. So, do not stay in house being a night owl, you can exercise if you determined and try to find time to exercise. The reason why you don’t have time to exercise- it’s actually-because you don’t really want to!