I think she is just so fat now that it's hard for her to move in her own weight, at least when it comes to jumping up/running. This is why I took her to the vet a couple of weeks ago because she was no longer climbing up on furniture and I even had to go get her a small ottoman to jump on and off my bed with. Fortunately the tests all came back fine other than the doc saying she was off the scale of obesity (she's 17 lbs and should be around 9). This is also why I'm getting a kitten at the end of March in hopes that an active kitty will motivate her. She's always loved to play with other cats in the past so my fingers are crossed that this will help.
In the meantime, I'm trying to get her to exercise some every day and it just isn't working. When I take her back to the vet in two weeks (after treatment for UTI symptoms) I am going to talk to the vet about ways to alter her diet but I don't think there is much we can do in that regard. She is on Science Diet S/D for FLUTD and is currently eating a little less than 1/2 cup of that per day which is the recommended amount for 10-12 lb cats. I have no clue what else to do! Does anyone have any advice?