There is no reason to "stay hyper-productive and focused" every single day. Just as the work ebbs and flows, a person's energy ebbs and flows.
The key is to develop _habits_ which serve you well on "off" days. Put forth the effort to do things like wake up at the same time, log in and do certain "ceremonies" of work, always do SOMEthing productive every day.
It's the exact same thing as forcing yourself to go to the gym every day no matter what. You don't have to set new personal records every time. But if you go and put in at least SOME level of effort, push yourself at least somewhat, then on the "bad" days you can just put yourself on autopilot and still put in a good (not GREAT, not superb, not fantastic, just GOOD) performance. And that's what matters.