I'm sorry about your diagnosis. That stinks.
My advice: Get your diet straight first. Eating a clean primal diet will lower your inflammation significantly and help a lot with pain levels. Just because OA is a degenerative disease doesn't mean it has to be a fast degeneration. You can slow it down a lot! (I'd venture to say maybe to a standstill.) Once your pain levels are less, start with walking, biking, swimming- something gentle and non-impact. I found this article on exercise that specifically mentions OA: Arthritis Diet: How to Prevent and Relieve Arthritis | Mark's Daily Apple This one as well. Take what you will from it: A Case Against Cardio (from a former mileage king) | Mark's Daily Apple. Best of luck!