I'm only 14 but what's the loss?

Yes. I am fourteen. Most people would say that 14 year-old don't really need to work out or run or anything unless they are extremely over weight. But what is the loss of us just going for a run? I just went for a VERY Short run, but it still got my heart beating. I don't really think I need to loss tuns of weight, or anything like that. But i just took my dog and ran up and down the street a few times. I usually would have done it for longer but it was getting dark. If i would continue this, then i would be in good shape when i get older. Now who does not want to be in good shape? Kinda random, but now i feel good after eating McDonalds, becuase i feel like i worked it off. Cool!