There are times when I am getting no where trying to convince myself to do something, even if I am well rested and am in an otherwise good mood. My brain is stuck in a kind of ineffective committee meeting where the Rational 'Let's build a better life' Brain is trying to convince the Lizard Brain to take some kind of action. After I notice that this back and forth negotiation has gone on for a long time (say, over 30 minutes), I then am reminded that if I was in an actual meeting I would fire the chairperson and put someone else in charge. The mental equivalent is to demote the brain for making decisions and declaring actions, because it's clearly being useless. And instead, I put my body in charge.
Bodies don't waste time sitting around, because bodies (especially feet) like to move. I find that if I let my useless brain fuzz out and put my attention into my body, I tend to move. Once I'm moving, this can often unfreeze the brain and I can then make some kind of decision to do something based on where my body happened to end up. Usually that's in front of my computer at some point, after I've eaten something and made my first cup of coffee.
It's surprisingly effective.