Stand facing the cable with a slight forward hinge at your hips, chest up, and a soft bend in your working elbow that stays fixed for the whole rep. Your arm sweeps out and back like you're opening a door, not pulling straight down or across your body. Lead with your elbow rather than your hand, and stop once your arm is roughly in line with your shoulder — going further just pulls your torso into the movement. Squeeze your shoulder blade toward your spine at the back of the rep, then let the cable return with control.