There are a couple of ways I keep myself motivated.

a) Creating deadlines. This can be highly effective IF you are able to take the deadlines seriously. My main problem with this is how there is no consequence of not finishing things before the deadline. This leads to my second option.

b) Set a goal. I use this the most whenever I want to finish a track. For example, Finish this track and upload it on New Years, which i ended up doing. I find this to be the most efficient way and I got a decent track done in 2 days for the new year release. If you get the deadline to affect something vital, you may end up getting things done faster and stay motivated to finish the track.

c) Listen to different music. If I end up being braindead and staring at my DAW for hours, I get away from the screen, lie on my bed and listen to music that is far from the genre I aim to make. Sometimes I take notes on what I like about those tracks and what I could port over in my production.

d) If you stop having fun, take a break. If music stops being fun for you like when you're frustrated on a track or can't get anything good started, stop and take a break. Go watch cat videos, eat food, sleep do something else you enjoy that does not relate to music production. The reason why many of us produce music even though we don't gain much from it, is because we enjoy the feeling of artistically expressing ourselves in this medium. Enjoy what you do, and keep doing it. Best of luck.