Hi Amanda and welcome.
Now, I can only speak for myself here (and I can also be quite long-winded at times)...but I personally hate exercising. I love walking...but that's it. I did the whole working out/gym thing years ago....but to be honest, I hated it and had to force myself to go...and realized that for me, it was not a good long-term plan for life....insofar as being a cornerstone of weight loss and management.
Just to warn you....I am a huge Atkins diet advocate but I also know that many here have had amazing success with a whole variety of diets, including low-calorie. But for me, low-carbing works fantastically. I also realize that there are many here who love exercising and have great success with it.
However....I would never want to see anyone exercise to the point of pain...especially if that pain is due to underlying orthopedic and neurologic problems, like you have. I've seen documentaries about weight loss facilities that treat hugely obese patients and they always start very minimal when it comes to exercising. It just seems to be the safe way to go.
I love to walk and even for me, I started out small. Only took short walks and didn't even attempt hills until I'd developed tolerance. With walking, you definitely build up tolerance and can build up to significant distances with no difficulty or pain. But I would definitely not encourage exercising to the point of pain.
Also...you do not necessarily need to aggressively exercise to lose weight. Like another poster blogged about....dieting is for weight loss and exercise is more to maintain health (cardiac, neuromuscular, respiratory, etc.)
For you, I would recommend things like walking, swimming...low impact exercising....to protect your joints and spine. And I would start out small and build up tolerance. And never to the point of serious pain.
deena