What Do I Do Now, with This Old Body of Mine?

for the first time since high school, I don't know how to exercise

I’m down to my last couple of weeks of physical therapy after my rotator cuff repair, according to my physical therapist. (Shouts out to Evolve Physical Therapy in Park Slope, they do great work.) I can now raise my left arm fully above my head, although it moves slowly and feels creaky, at least until I’m warmed up. (And always, always with the clicking.) I can go into full interior rotation and close to full exterior. Two weeks from yesterday will be six months since surgery. People I’ve talked to who had the surgery tell me that it’ll be a full year before I really feel back to normal, but the direct medical work of regaining motion is coming to an end and I will now focus primarily on rebuilding strength, on my own. Which means that I now have to confront what to do with myself as far as exercise goes. I confess I’m kind of at a loss. Immediately after surgery, I was incapacitated and couldn’t do anything physically with my left side, and for the past five months I’ve restricted myself to PT, so I didn’t have to make any of my own decisions. Now that’s coming to an end, and for the first time since I was a teenager, I don’t know what to do for exercise.