If you can, actively examine your thoughts/emotions and dissect them from a distance so to speak, when you feel stuck and have trouble to reach for motivation.
There's a power in simply accepting that it's just a feeling, whether you're tired, motivated, hungry... The feeling that you want instead, is a sort of disassociation. The stronger the feeling, the harder it will be. And then you just do the thing you need to do despite lacking motivation or being tired or whatever.
There's something liberating about it that is a bit difficult to put into words. Like "fuck it, I'm going to do it anyway". Sounds a bit stupid, but it's not entirely wrong.
However it's not a magic trick, but rather a kind of thought muscle you can try to train so to speak. It works for me increasingly, despite being quite terrible at this kind of thing. Or rather two muscles: One is creating a distance/objectivity to your feeling or state of mind, the other is to start the action. Sometimes the second part is almost automatic once you do the first part well from my experience.