And what if they can't? I'm overweight, not obese but I can do very limited exercise due to my spine. I can walk (but < 2 miles) or ride my bike (< 2 miles). It's not stamina or lack of willingness as I love to walk and double that for riding my bike, but my spinal issues. Any fuck-ups = herniated disc at worst or bad headache at best.
I lost weight (13% of my body weight) but I can't lose more, and I'm having a hell of a time keeping it from coming back, even though I changed how I eat (not back to bad eating habits - I figure that the eating changes must be permanent.)
So it's not all lack of willpower or effort, sometimes your middle-aged body just screws you.
Believe me when I say I understand that.
I myself have a herniated disc in the lumbar region.
I also had my tricep tendon tear off the bone, for which I had to get surgery. I got the surgery pretty late, so I can't recover 100% of my strength previous to my injury. I'm at about 70% which is astounding, and more than I expected. What it took to get there could write a book.
So between those two injuries, I've been cut out of doing a lot of what I used to do before, but I've basically just decided to work around my injuries as best as possible.
Glad you are making a change though.