"If your dog is fat, you're not getting enough exercise."
Dog owners walk as much as 2 hours more a week than people without a furry friend. When Fido needs to get out and stretch his legs, he lets you know, and on go your walking shoes.
Can't have a dog? Here are some other ways to get walking: http://www.realage.com/news_features/tip.aspx?v=1&cid=18561.