MAIN MOVE: Ponytail extensions

Stand with feet hip-width apart. Hold light dumbbell in right hand, arm extended straight overhead, left hand supporting right elbow (A) to prevent it from flaring out. Bend elbow, lowering dumbbell behind head (B), then press back up to start position. Do all reps, then repeat on opposite side.

MAKE IT HARDER: Use the heavier dumbbell.

MAKE IT EASIER: Hold the ends of a single dumbbell with each hand so it's horizontal to work both arms at the same time.