Gotta love that rush of endorphins, that gives people a runner's high. There's nothing like a good workout to release these endorphins, which will lower pain and bring some feelings of euphoria. (Dating tip: people tend to become a little hornier during shared exercise, too.) Aside from the immediate lift in mood, becoming physically healthier fosters more pleasant regular moods that carry over from day to day. Of all the rushes you can get addicted to, runner's high is by far the healthiest.
