It was Christmas afternoon, my older son was curled up on the couch with a book I’d given him, and he wouldn’t stop giggling. The book was You Might be a Zombie and Other Bad News, from the editors of Cracked.com , and I'd known as soon as I saw the title that the book would be a perfect gift for my son. I hadn't necessarily planned to purchase anything the fall day I'd been browsing through my local bookstore, but a quick flip through confirmed the notion, and soon thereafter my Christmas shopping season had officially begun. This son is 24 and I’ve read aloud to him his whole life long. A fringe benefit is that he also likes to read aloud to me. So when I asked him what was so funny, he started reading from a chapter called “Four Things Your Mom Said Were Healthy That Can Kill You.” The countdown was in reverse order and began with #4: Exercising. He read: Exercise is good for you. Exercise is hard. Therefore the more you exercise, the better off your body will be...