Book excerpt: Salad instead of steak? Exercise? Skipping that second beer or glass of wine? Healthy habits are the worst. Blending humor and irreverence with the science of behavior change, a health psychologist and runner who's never experienced a ''runner's high'' offers practical, counterintuitive strategies and a playful approach to help readers live a healthier life-even if they really want to just sit on the couch and eat ice cream.