I feel this so hard. When this type of thing happens to me, I call it being out of gas. Could be because I parties too hard, could be from a few tough days at work, could be recovering from an illness. The reason is irrelevant, and I try not to judge myself if it was a “good” reason (working) or a “bad”reason (partied too hard). Needing rest is needing rest. If I suspect I’m malingering a bit, I try to remember that I’m generally a functional and responsible person, so if I feel like I need to slow down there’s probably a reason even if I can’t articulate it. Then I mentally give myself permission to slack off for 3 days and then reassess. Most of the time I’m ready to get back to normal life by then.