MAIN MOVE: Handbag curl
Stand with feet shoulder-width apart, arms at sides, a heavy dumbbell in each hand, palms facing in. Bend left arm to 90 degrees, dumbbell vertical. Hold that position as you bend right arm and curl dumbbell to shoulder, keeping elbow in to side. Complete all reps, then lower both arms and repeat, holding right arm at 90 degrees.

MAKE IT HARDER: Hold dumbbell in the stationary hand with palm facing up so it's horizontal rather than vertical.

MAKE IT EASIER: Alternate curling each arm up to shoulder without holding either arm stationary.