My new goal is three times a week. I did exercise three times last week, and it took me two days to recover. I swam twice and went to the gym once (pool was closed). I found this machine that's kind of like a stationary bike but not. You just alternately bring your legs up and down, knees bent. Fortunately, my knee didn't not blow up the next day. I did 40 minutes, which is more than I imagined I could.
I have lost 36 lbs now, and I still can't walk. I've started Humira. I've got two months to make this happen -- be able to walk so I can work. It looks more and more like it will take more time than that. Or it might not happen at all, in which case I'll have my second knee replacement.