When David was 5, his mother recalls, he decided that he had two careers to look forward to. He would be a professional football player, for one. In the off-season, while the other players were recuperating or doing whatever it is that pro football players do when they're not running or passing or slamming their bodies into each other, he would be a neurosurgeon. His mother has no idea how, at 5, her son might have heard about neurosurgeons or what they were or did, but he had. The first day of his medical career, he promised his mom, he would take out all of her frayed nerves and fix them. "Somehow he knew about neurosurgeons," she says, "and he knew that my nerves needed fixing."