Stand up straight with your affected arm by your side and elbow bent to 90 degrees.
Hold a resistance band, or pulley in your affected hand.
Ensure the other end is tied securely.
Stand sideways to the band with your affected arm nearest the attachment point, so that the band travels away from your body.
Keeping some tension in the band, step further away from the attachment, and then step back in.
Continue this movement, ensuring you keep your forearm pointing directly forwards.
Keep your shoulder blades relaxed throughout this movement.