Just one more note: I don't think it's necessary to lose a lot of weight in order to be more fit. For instance, in the last 15 months or so, I upped the intensity and frequency of my workouts and walks, and over that time, I only lost about 10 pounds. HOwever, I GREATLY improved my flexibility and my cardio. I went from taking about 19:20 to walk a mile to being able to do a mile in about 16 minutes. I can jog for 10 minutes straight without getting winded or getting a stitch in my side, something that I couldn't do when I weighed 60 pounds less than I do now.

I'm not saying this to dissuade you from losing weight, only saying that getting fitter doesn't require massive weight loss.