Work Your Abs in Just 15 Minutes
Strengthen your abs and obliques by sitting on a large ball with your feet flat on the floor (top illustration). Walk your feet forward, letting your entire back rest on the ball and keeping your thighs parallel to the floor. Cross your arms over your chest and slightly tuck in your chin (bottom illustration). Contract your abs and exhale as you raise your torso about 45 degrees. Pause, then lower, inhaling as you go. If you feel unstable, move your feet farther apart. Repeat 8 to 12 times.