I think it’s possible to be in constant motion, and rest at the same time.
It’s called rest-in-work, and it’s the same principle long distance swimmers and marathon runners use to keep going.
Even in the middle of your busiest day, you can pause. You can rest while working, because it’s not really the amount of things each day that tires you out. It’s doing three things at the same time, or doing one thing and thinking about the other six things you have to do next.
Actually, if you do just one thing at a time, it all becomes manageable. Try it.