Steady on the Plank
(Strengthens abs and shoulders)
Get into a push-up position, with your elbows and toes on the floor. Keep your stomach pulled in and buttocks tight and your eyes looking at the floor (ignore the fact that you have to vacuum). Hold the position for as long as you can. If you can last more than a minute, make it more difficult by lowering your chin 20 times out in front of your laced hands or by trying to balance on one foot.