how do you deal with fatigue and reluctance to play?
There is nothing wrong with simply taking some days off when you don't feel like playing.
In fact, this is probably the best thing you can do when feeling not the best... because, the worst thing you can do it force yourself to play a poker session when you aren't feeling good, and then you'll later blame yourself more for any losses accrued because they were unnecessary.
This was a mistake I made when I was first starting out, because I had monthly hand targets and I didn't want to miss them. So, even if I wasn't fully feeling up to it I'd still put in my
hands, and many times I would wipe out many days of work and results with one bad session.
Fortunately, I later realized that the monthly hand goals were just numbers i chose, and that didn't have to mean anything... specifically that there was no reason to think it was the end of the world if I didn't hit my hand target that month. Better to miss a goal that I had simply 'made up' for myself rather than lose money needlessly.
I think this video I have is sort of on that topic, the more 'in order' you can have your life and your work area, generally the more energy you'll have available to play poker.
If you're not feeling up to it tho, there's no reason you should feel like you 'have' to play.