Start standing with your feet shoulder-width apart, holding a dumbbell in each hand. Extend both arms overhead, holding the dumbbells with a neutral grip (your palms should be facing in). This is your starting position.
Without moving your left arm, bend your right elbow to lower the dumbbell down to chin height. On an exhale, extend your right elbow to return to the starting position. Avoid "shrugging" your shoulders by drawing your shoulders down and back. This counts as one rep.
Without moving your right arm, bend your left elbow to lower the dumbbell down to chin height. On an exhale, extend your left elbow to return to the starting position. Avoid "shrugging" your shoulders by drawing your shoulders down and back. This counts as one rep.
Continue alternating between right and left sides for 20 reps total (10 reps on each arm).