Personally, when I get into this kind of rut I get myself something to do for the next day. See a friend, work, volunteering, sport. Doesn't matter. The thing that matters is that I make arrengements with someone and they're expecting me. It's not like if i decided I should do something tomorrow and can change my mind in the morning. Somebody's waiting for me, I have to go. Once I get out of my house, everything gets easier. I'm already out so might as well go do some errands. Then why not buy some food to try that new recipe? I come home and it's time to cook....etc Once I gain momentum I find it easier to keep going.
I definitely identify with this. For me a huge motivating factor is the embarrassment of letting people down, so I need to put myself in situations where I'm accountable to other people. Otherwise I stagnate. When nobody is relying on me directly, I struggle to get anything done. When I have somebody waiting for me to finish a job on Wednesday and I'll look ridiculous if I don't deliver, suddenly I'm super motivated. Consequently I've learned to structure my work life/social life/general goals in such a way that I'm always accountable.