And exercise IS part of the plan that I tend to overlook. I won't say forget, but conveniently overlook. That is something I need to work on.
I have a suggestion that worked well for me many years ago, long before I began the McDougall Program approach: Set an easy goal for exercising every day, for a week. Then make the next week a little more ambitious; and the week after that still more ambitious.
Example: Brisk walk, one block, out and back, every day for the first week. Easy.
Then do two blocks out and back for the second week. And so forth until you reach an acceptable time limit (half an hour to an hour per day?).
Then with the distance fixed, gradually increase the speed.
Then when you have reached that limit, pump a little weight in your hands as you walk.
The point is that there should be a plan
and it should lead to gradual improvement. "Stay the course" isn't good enough until you have reached your limit.