I also was "one of those kids" as I did my first marathon at age 12. I had started running in elementary school gym class and loved it. My Dad and I ran a few races together and had a great time. After he did his first marathon, I wanted to do one. I trained by myself; he never pushed me (I think he thought I would soon give up the quest). I ran all through high school and 4 years of D1 cross and track. I am still running and now looking forward to entering the masters category. If my kids want to run I certainly wouldn't discourage them. I think the key is that it was something I wanted - I was never pushed nor would I push my kids. I still love traveling and racing and training. The friendships I have made are fantastic.