Well, sports are healthy for a young growing body. You get exercise and it's fun! You can meet a lot of new people and make friends. It's competitive and some sports have strategic gameplay. Soccer, tennis, volleyball, swimming and many other sports are great examples for ones you could try. Instead of sitting at home, like a couch potato and playing video games you could go outside and play some sports that are good and healthy for your body.
I hope I gave you a good idea on what you should write about!