Most teenagers say they play sports because they like the competition and the social aspect, or because it helps them stay fit and looking good. Now there's an even more important reason for teens to exercise, like lowering the risk of serious diseases, even cancer
In women, certain types of breast cancer tumors feed off of hormones like estrogen. Exercise helps a woman's body fight this type of reaction.
Guys can get the same benefit too. While exercising doesn't affect their hormones in the same way, it keeps them lean and healthy.
According to the American Cancer Society, obesity is just as dangerous as smoking tobacco, when it comes to cancer risk.
Doctors advice...teens should exercise five days a week to help their bodies build up their biological shield.