Thanks for the counterpoint and the exercise tip. I'll actually try it tomorrow, maybe mix it with my usual "idk what I'm supposed to do so maybe some burpees". But my experience so far was that nothing ever changed noticeably beyond the early days, in which the major change was just the ability to do 1.2-1.5x as much pushups/planks/burpees as the day before.

As for dieting, I had a limited success with it - managed to visibly drop weight in few months, though I regained it over the year after I dropped the diet regime. Problem is, the diet was moderately distracting on a daily basis. The bigger problem, however, is that the vastly reduced variety of meals I consumed made me dislike some of them, and make others feel bland - so at this point, I can't see myself going back on the same diet, simply because I'm repulsed by the idea of eating those same foods again.

And back to the big point - as far as I checked, neither my weight, nor diet, nor physical activity seem to have had any noticeable correlation with my sleep patterns, mood, energy levels or ability to focus. I've never felt any positive effect within days or weeks of improvement in physical activity or dieting - nothing above noise floor, and especially nothing I could clearly attribute to lifestyle change.