Get into a high plank position with your shoulders directly over your wrists. Lift your left foot to bend your bend knee and bring it towards your left elbow. Tap your left elbow if you can, tightening your left oblique. Then, bring your left foot back to the starting position. Next, lift your right foot to bend your right knee and bring it towards your right elbow, tightening your right oblique. Bring your right foot back to the starting position. This is one rep. Continue alternating sides for eight to 12 reps.