[korijn]

After going through the exact same thing (ulnar nerve RSI, pain in my wrist and hand, caused by my shoulder), my PT recommended a suspension trainer. It's cheap, doesn't take a lot of space and you can adjust your body angle to "set the weight". For example, if push ups are too hard, just reduce the angle until you can handle it. This way you can vary load from nothing up to your body weight. Pretty easy to set up too (I just bolted it onto a sturdy wall).

He recommended I exercise every day, I picked just before bedtime as a constant so it's easier to remember.

Instead of sets and repetitions he gave me the rule to just keep going with each exercise until I can't anymore (and that doesn't take much in the beginning).

Finally he gave me the advice to always choose exercises from three different categories: push, pull, and legs.

So you could get started with (1) pull ups/rows/flys, (2) standing push ups and finish with (3) squats for example. There's tons of charts online. Rows and flys are good for strengthening your shoulders.

Also, remember to take the exercises slowly and be mindful/aware of your motions and posture. Don't rush through them, put some music on, put your phone away, focus on the exercises! Quality over quantity.

Hope this helps. It worked wonders for me!