Crunches get boring, but this bicycle move amps up your typical ab workout and targets the obliques, the muscles on the sides of your abdomen. Add this move to your typical core workout, or try it on its own.
How to do it: Lie flat on your back with hands behind the head, legs and feet lifted, and knees bent to a 90-degree angle. Lift the head and shoulders slightly off your mat. Twist the torso so your left shoulder moves toward the right knee. At the same time, extend and lower the left leg.
Alternate sides for a total of 10 reps on each side.