The stress response exists for the purpose of survival. When we experience stress, our sympathetic nervous system activates, blood pressure and heart rate increase, and often we begin to sweat. These physiological reactions prepare us for "fight or flight." Our bodies are at optimal physical performance and alertness levels, and we are therefore optimized for survival in a physically challenging situation. Sometimes we use this physiological activation to our advantage: Consider a champion weightlifter who, prior to lifting an extremely heavy weight, "pumps himself up." By doing this, the weightlifter is attempting behaviorally to elicit a stress response from his brain and body in order to achieve the highest level of physical performance ...