I go to the gym. I have to do a particular exercise (dumbell bench press, lat pulldown, whatever) at a specified weight for a specified amount of reps and sets. I do it, no problem. Couple days later, I have to do the same exercise, with the same weight and sets and reps, and I am DOGSHIT at it. Can't even do a single rep. This makes me feel sad. Another couple days pass, I can do the exercise just fine.
It's a weird spectrum. One day I'll be able to do an exercise fine, the next not at all, the next I can kinda do it but not to the rep amount I want, the next I do way more reps of it.
Could someone explain this phenomenon to me? Shit is annoying.