I'm not saying don't, I'm saying be careful. I used to be able to do loads of squats - now if I do more than 10 at a time I will be barely able to walk next day! I CAN do stairs now, though not too many (now, I couldn't before pred). It is a question of starting with just a few, say 5, and if that is OK next day, add another 1 or 2. It's really also better to allow a day between exercise days to allow recovery. Everything now takes longer to get to the same level of training but usually you can get there eventually.