Nothing to do with acquired knowledge my man. Sometimes I have found I just kind of wander away from the most fundamental philosophy of physical training: you have to do progressively more total work over time, whether it be weights used, total weekly volume, etc.
And that means training hard.
Sometimes I find myself slacking, doing static volume that will maintain me but in no way progressing me, even though I can go harder. That ability to push further is so simple and critical, I forget it. I get content.
How many times have I done the same hamstring curls or shoulder raises and not tried to dig for even that one extra cheater half rep, or I could have added a rest pause set of 3 at the end of my last set but kept it easy?