STARTING POSITION:
Select the appropriate weight of the dumbbell. Sit on the floor and place a flat bench behind your back. Your shoulder blades should rest on the bench and your feet should spread at shoulder width apart, just in front of your hips. Grab the dumbbell and fully extend the arms so that they are perpendicular to the floor. Contract your pelvic floor and core.
MOVEMENT:
Start lowering the dumbbell towards the floor until the biceps almost touches your ears and you feel the stretch in your pectoral and dorsal muscles. Inhale during the descent. Return to the starting position in a strong movement by extending your shoulders while you exhale.
TIPS: While your are doing the exercise, move only the shoulders joint, make sure you don't move any other part of your body. The exercise key is quality over quantity. The trick is to perform the exercise using proper form.