In reply to AddPop:
One handed climbing - this is my response to various finger and hand injuries, and it keeps me in shape and stops me getting too out of practice.
It helps you to use alternative moves, find different ways of using a hold, slows you down and improves your balance and footwork. One useful move is a semi dynamic move up to the next handhold, such that at the top of your (slow) spring up when you stop rising before you come down again you are briefly motionless and can just reach across to the next handhold. Elbow hooks are sometimes useful, chin hooks are best avoided!
All this works much better while top roping, and while climbing lower grades than before. Lead climbing is harder, you always have to clip with the bad hand and be relaxed and ready to let go and fall at any moment (no desperate grabs !).
Bouldering is harder still as falling onto the injured part is a no-no, and down climbing one handed is a challenge!!
Finally, swimming is very good exercise. I once broke my leg just before a skiing holiday (gutted !!) so my parents still took me to Italy. I spent the week in the pool looking out the windows at the mountains, and got a lot strength back in my weak jelly like leg. I even made it (determinedly) out onto the slopes one day hopping with a pair of ski sticks...