Running, and lots of it. It's the single best way to lose weight. I typically run 8-10 miles a day, 5 days a week. Although my eating habits aren't the healthiest, I make up for it with insane workouts. Situps and pushups when you wake up and before you go to bed will help with definition, too.
KagomJack said:
My girth isn't anything to bitch and moan about in long, elaborate paragraphs.