I agree with everybody. I used to get forced outside and eventually I'd go play or do something. Once 2000 hit and I got involved with computers and what not, I started not making friends and not wanting to go outside.
I was fat before then but that's when it got worse. I think it's definitely worthwhile to "persuade" if you will.. your children to do what you know will create positive healthy habits later. Let them be kids but don't let them hermit like I did, it's worth the fighting and complaining at the time to make them do something instead of seeing them sad.
But yeah he hit the nail on the head, I'm not big on "politically correct"