Hi lornameg, you certainly shouldn't feel guilty for not exercising if you are unable to exercise.

No thinking person would say you should.
For the rest of us without mobility/health issues, it is a little different, I think. I'm 65 years old and am in better shape than I have been in years, partly due to a better diet

and pounds lost, but also because I walk fast (to get places) and slow (for the dog) and do zumba several times a week. I plan to be doing the same thing at age 75, God willing.
My husband said that, before, I was starting to walk like a little old lady, slumped over and kind of unsteady on my feet. It was not good! When I caught a glimpse of myself in a mirror or window, I really hated it.

Now I walk with confidence and energy because I feel strong and fit, and because I know I look fit. Knowing this, it makes fasting a whole lot easier.
So, count me with those who say that it is more complicated than just calories in, calories out. It is a WOL even more than a WOE.