Also: Under-stimulated -> anxiety -> Have To Do Something, Anxiety Driving Me Nuts-> DO ALL THE THINGS -> stress!! -> stimulation burst because of stress -> overwork -> over-stimulated -> burnout -> depression -> under-stimulated
Having disciplined myself to break such downward spiral cycles helped. That is, if I feel stagnant, I force myself to do something, anything else. Maybe it could help you too?
I had this happen a lot, then I was zapping around the TV aimlessly for hours.
It turned out I was out of energy. Mental battery empty.
One of the biggest changes was - I trained myself to have rest days where I do "nothing" every week (that is "nothing which taxes me. mentally", so also no meeting with friends or so). As long as I have enough energy left, I can compensate for a lot of stuff - so I make sure I have enough energy. (Playing on the console is fine, watching TV is fine, cooking is relaxing me, even doing a limited number of chores)
Those undestimulated days are rare now, compared to 4 years ago.
I can tell it's happening, I'm low on brain-reward BECAUSE I'm not working on things that are meaningful or solving interesting problems or whatever.... And like timidly taking on a half-pipe, I don't have enough "juice" to make it to the other side and just settle in the middle... Well, crap, now what?
Too exhausted and sad to work on things that will make me feel less exhausted and sad > doubting self > loathing self > deep funk > hopefully wears off in a day or two...