Scapular retraction side lying rolling ball (Scapular retraction stabilization, rolling ball, side lying)

Lie on your good side.
Place your weaker arm on top of a stability ball or football so that your arm is a similar height off of the floor to your shoulder.
Bring your shoulder blade back in a small movement towards your spine.
Slowly roll the ball upwards toward your head whilst maintaining this position with your shoulder blade.
Roll the ball down, maintaining the shoulder blade control.