"Is it about a schedule, or is it about a desire to be healthy such that the desire is strong enough to overcome the inertia of the couch (bunk)?"
It may be a little of both.
I don't know. I DO know that when I was a semi-pro in the hunting and fishing industry and I was in the field several days a week, I dropped over 80LBS in 6 months. I felt good, fresh air, lots of walking. I also eat about 1/2 as much when in the field that anywhere else. I guess because both my mind and body are occupied.
This is a VERY BORING industry. It does little to force the use of brain power. It is also very difficult, at least for me, to get motivated to work out in a stinky parking lot, stinky gym or stinky exercise room in a truck stop. I don't do well when enclosed or surrounded by stinky stuff. Working out is also kinda "unnatural". exercise that is gained through work or play is "natural".