Hey Barney - something I did .............
Purely my thinking but the human body gets used to routines - over the years and when those routines change substantially ""stresses"" happen.
When I retired I chose to sleep in a half hour every morning (6:00 now 6:30) and try to come close to the activity level 'from before'.
It drove my wife crazy but the transition for me was easier. Later, of course, aging and medical considerations modify things some but it was more gradual and easier to live with than any sudden change.
"Keep At It" and post as you do stuff.
Joe