One workout do 3 sets of 12 to 15 reps on each side. For your next workout, do 4 sets of 6 to 8 reps per side.
How to do it: Grab one of the lighter dumbbells in your right hand and get into a side elbow plank with your left forearm resting on the weight bench, right leg crossed in front of left. Lift your right arm until it's in line with your shoulder. Lower the weight towards your hip (but don't touch arm to body). That's one rep.
