Post-op workout?

I was wondering if anyone had any ideas about a post operative workout that I could get started on, I just had my achilles tendon reattached two weeks ago, but it seems stupid to take 6 weeks off (approximately, he hasn’t given me an exact date yet) as the doc recommends. Also any form of cardio that has worked for people might help too, because where I was stuck in bed for a week, I gained about 15 pounds since my surgery, and I want to get back in condition. Any help would be greatly appreciated.