Check out Women's Health's FitGIF Friday every week for fun and challenging new moves to make your sweat sesh really count. Here's this week's exercise:
Stability ball pushup: Push yourself (get it?) to the limit with this challenging pushup variation. Adding a stability ball to the mix helps shift the majority of your weight to your upper body, which strengthens your arms, shoulders, and abs like crazy.
(Get more abs-sculpting workouts from Women's Health's Look Better Naked DVD.)
