Hi everyone, I am new to climbing and am loving it, but one thing that im having a real tough time with is just hanging from one arm while bouldering. I have had shoulder surgery on both shoulders because of dislocations in the past, so my shoulder joints are a little weaker than most peoples, and i also want to make sure I do this right and dont injure myself.

What kind of things can I do to strengthen the shoulder joint and the tendons around it?