Frank, swim.

Best wishes! Maybe you might bring a tablet or a cell phone with access to this Grokker collection to an appointment with your doctor. You might ask your doctor to scroll through the 145 videos in this Grokker collection to advise you about which videos he/she thinks might work for you. Good luck, and congratulations on your wish to exercise!
Mobility, Recovery, Physical Therapy: https://grokker.com/yoga/collection/mobility-recovery-physical-therapy/603eb9efb356ab7d31b83fa0
Also this additional collection might be of help: Pranayama and Chair/Office Yoga https://grokker.com/cooking/collection/pranayama-and-chair-office-yoga/6032caad6cd106116a987af1