Grab a pair of dumbbells and stand on right leg with left toe pointed out to the side, lightly touching the floor. Bend right arm, bringing dumbbell to just outside of shoulder, and extend left arm up, palm facing forward. Press right arm overhead and bend left elbow as left knee lifts up toward chest. You should feel your left obliques working to lift knee as high as possible. Return to start. Do 15 reps, and then repeat on opposite side.