I've done quite a bit of yoga. I like that it can be as relaxing or as strenuous as you want to make it. Why don't you go along and take a class or two and see how you get on?
I find the key to exercise is to do something you enjoy, then you will stick with it. I really have to push myself to run, and so I find I keep making excuses to not go. However, you can't keep me out of the dance studio. It's great when exercise is something you actually look forward to instead of dreading.
Do you have a friend who could join you in an activity? That always helps to keep you on track, and they may be able to help distract you from some of your sensory issues.