this is something I also struggle with: I do not have a well formed answer since I'm still figuring it out, but maybe my experience might help you.
I kinda make myself do it, like an obligation. I tell myself there is no reason for me to just drop it. but on the other part, if I really don't want to do something, then I'll just leave it because why would I make myself go through that.
sometimes I just do it just to see how it would make me feel once it's finished. sometimes I do things with zero energy or with a mad mood and that's okay too.
I don't wait for the energy to appear, because it's not something you can just spawn magically. spending time with family and friends (it might sound cliche) actually works, your brain is distracted and there's this urge where you want to do something with them, as minimal as it is. it keeps you centered and say 'there's things I have to do and I will do it' bc of adrenaline. (or at least I see it like that)
so to do things and to not get my brain to get used to do nothing, I don't stay in my room. Sometimes I light incense and walk around the house with it, to get distracted and feel like I'm doing something. If I start something and then leave it unfinished, I don't tidy anything, I just leave it there like a visual reminder. (being unorganized makes me itchy, so I'll finish it)
uhhh motivation? I don't know. I mostly think of others instead of myself. It doesn't have to be family or friends, it can be your favorite artists or heroes or whatever.
I think I ran out of words, I hope this might help you a little bit. xo