You sometimes need rest? Don't try to work harder, try to work less. Your body and brain might be telling you it's recovery time.
I know I can force myself to be more productive, and can work really hard, and will eventually reach burnout, because I force myself to work hard really efficiently. So yes, I found some ADHD brainhack to study, work, raise a kid and tend a small farm, all at same time. It worked great for about 7 years, then my energy was depleted.
Nowadays the only thing I'll get busy for is fighting for the 4-day work week and against the productivity myths people tell themselves.