I started with a tear that then became Frozen Shoulder. I could not lift my arm above chest level. I swam and did stretching and pushed a little beyond my comfort level.
One year later (yes.....one year) I have 90% use of my arm and shoulder. My friend who is a DR also had a Frozen Shoulder and he said most cases resolve themselves completely without treatment in 1-2 years. He is a cancer surgeon so I'm pretty sure he was informed on his decision not to operate before he would risk his career with his own shoulder issues