Cardinal directions with the left shoulder
In side-lying on your right side, you systematically go through movements of your left shoulder in the cardinal directions: forwards, backwards, upwards, downwards. You lead with your left shoulder, or with your left hand and your left arm extended. You go through various differentiations.
After the lesson you will likely be able to move your shoulder much further, much more refined, and in ways you could not move your shoulder before. The inability to move the shoulder, therefore, was not a matter of structure or muscle stiffness, but it was something in the brain, an inhibition. Take rests on your back in between movements or whenever needed.