Do The Double Crunch
Sit facing a low-pulley cable with a bar attached. Place the bar between your feet so it rests across the tops. Lie flat on the floor, knees bent 90 degrees, with your hands on the sides of your head, elbows out. Slowly curl your head and shoulders up as you tilt your pelvis and curl your legs toward your chest. Hold for 1 second, and then return to the starting position. Do 12 to 16 reps.
Illustration by Kagan Mcleod.