Start in a plank position with hands under your shoulders. Lead with your non-dominant arm by lowering down to your elbow by placing your elbow where your hand was originally. Then repeat on other side so that you are now planking on both elbows. Now come back up by placing your non-dominant hand where your elbow just was and follow with other hand so you are back in pushup position. Repeat same number of reps leading with your dominant side. Drop to knees to modify.