Assuming you play paintball (that's an HK Army icon, if i'm not mistaken), there are some great drills you can do to really burn up calories. Work on running and shooting around a pole, or up and down a field. practice snap shooting from a "squat" position. or you can do run-slide-crawls up and down the field... between the practices, games and other training, I lost about 40lbs in one season of paintball. Good luck to ya!