As a kid, you were probably told to wait 30 or 45 minutes after eating before doing any strenuous activity or exercise, such as going swimming. Well, if you've taken this childhood lesson—though some experts would call it a myth—into adulthood, and the first thing you do after eating a big meal is to relax on the couch, we've got some news for you: You should go for a walk. Yes, if you go out and pound the pavement really hard and try to break a big sweat, there's a chance you may experience the resulting...