Most people I work with treat rest as something that has to be paid for in advance. Finish the list, clear the inbox, get ahead – then you may stop. The trouble is that the list is a renewable resource and the permission never arrives.
What makes this so durable is that it works, for a while. Deferring rest genuinely does produce more output in the short term, which is exactly the evidence the habit needs to keep going.
A different accounting
Try treating rest as an input rather than a reward. You do not earn sleep by having a productive day; you have a productive day because you slept. Nothing about the logic is new, and almost nobody applies it to their weekends.
The practical version: put the rest in the calendar first, at a fixed time, and let the work arrange itself around it for four weeks. Four weeks is long enough to notice, short enough to agree to.