Eccentric shoulder horizontal adduction with weight - unilateral

Lie on your back on an bed with a weight in the hand of your affected side.
Start with your upper arm out to your side, your elbow bent and with your forearm pointing up to the ceiling.
Push the weight towards the ceiling, straightening your elbow.
Keeping your elbow straight, slowly lower the weight out to your side.
Return to the start position and repeat.