Help for my mom!

Okay, my mom is obese, borderlining on the morbid side. She is fully aware of her weight problem and has been trying to control it for a good amount of her life. She's only ever been a healthy weight when she was eating "nothing but rabbit food" all day every day. Of course, she felt like crap still. That was 20 years ago. Since then, she weighs a lot more (I'm not even sure, but I'm guessing 325 to 350). She's 5'3", 62 (almost) years old and has some medical issues. She has Rheumatoid Arthritis, a calcified thyroid, asthma, allergies and probably the absolute worst thing is that she has four cervical vertebrae fused, so she can't move her neck. She's also going in to get a few in her back fused since there is no fluid getting through in there. Those are all from a car accident (with a logging truck on the other side) 35 years ago. Despite all this, she does do her Wii Fit every day before work. 45 minutes doing the step routines and then another 15 on the boxing setting. It's not exactly going to make you fit and toned, but it's something. Weekends she can get on a recumbent trike and go biking with us but that can't happen very often because there aren't a lot of biking lanes where she lives, so she leaves her trike here where there are.

Anyone have a success with working past things like this and have something to share that would be beneficial to her? Other than that, she's an accountant and sits at a desk all day.