Purpleinheart,
Though I don't pretend to have the food portion of this figured out, the activity part of this I LOVE! I have always loved to exercise (which is why my 40 lb overweight body is in shock )
and here's why: I love the time to myself, blasting music nobody else in my family appreciates (through my earphones, of course). I suggest getting an iPod or a TV to use while using your reformer (are you talking about the Pilates machine or the bands?) or while simply walking or hiking. If you can't stand long periods of exercise, start out with 15 minutes or so. I keep tract if time by either songs, programs or trying to pass people while walking (I pick out the weak ones and move on past

I jog for one song, walk the next. Or, I up the ramp to 12 on my eliptical machine for 5 minutes then back down to medium for the next 5 (and the next song). If you can watch television, you could use the time of the show to workout, the commercial to rest, etc. I guess the bottom line is thinking of it as time to yourself. Time to get your blood flowing, your mind clear and your body energized. Even if only for a short time.
That being said, losing 90 lbs is a huge accomplishment! I'm very impressed and sure you will be a success story.
Good luck.