I like to do cardio after weights. My theory being that after weighlifting, one is tired. Therefore, you MUST exert yourself while doing cardio. Then again, my only cardio is running on the treadmill from 6.5mph to 8.4mph. By exerting yourself close to the point of puking, the body is being drained and I love that feeling because it produces results. Then again, it is my unproven theory that works for me. Keep on working...