I also agree on the yoga
One other thing that I adore is these videos called Walk Away The Pounds. It's basically walking in your own home. They are extremely low impact and, well, if you DO get tired, you just sit right down. I love to walk, but I'm always afraid to walk to far and not be able to get back home lol
But seriously, I get some extremely bad days, and usually I'm still able to do these with no problem. Just do a search for them on google, you won't have any problem finding them
Good luck!