STARTING POSITION:
Put a fitball next to a pulley and sit on it. Your right shoulder should point to the pulley. Place the pulley on a position above your head. Select the appropriate resistance in the weight stack. Grab the handle of the pulley of your right hand, and move your hand in front of you. Your elbows should be slightly bent and your hands should be slightly under your shoulders. Contract your pelvic floor and core.
MOVEMENT:
Start opening your arm to the side until you feel the stretch in your pectoral. Inhale during the movement. Using your pectoral muscle, return to the starting position in a strong movement while you exhale. Repeat the movement for the specified amount of repetitions and then switch sides and repeat with the other arm.
TIPS:: The exercise key is quality over quantity. The trick is to perform the exercise using proper form. Your arms' line should always match the line of the pulleys. While your are doing the exercise, move only the shoulder joint, make sure you don't move any other part of your body.