I find that the thought of needing motivation can be kind of a distraction in and of itself, since most habits are formed and repeated without the ongoing need for a source of inspiration or incentive - you just keep doing it. Momentum is its own driving force. The question becomes more about how to get up to that level of momentum where it's harder to stop than it is to keep going.
For that, I don't want to just say "have discipline" but it really is just preparing yourself to work when you might not really want to. Have a schedule and a minimum output per day or per week. Maybe give yourself a little treat if you meet the goal you set for yourself, as long as that goal has you working consistently and frequently. You'll gradually feel less and less like you're forcing yourself, you won't feel stuck or dread getting started because you've built up momentum. You'll have experience with getting your hands moving even when there's nothing really inspiring you in the moment, and at that point, all you have to do is maintain momentum - way less effort than building it up and letting it fizzle out over and over.
I always use a gym metaphor: if you need to feel great about going, you never will. You'll see something like a movie with a workout montage that inspires you to go once or twice, but you'll get sore the next day and let that dissuade you from going back regularly. But if you work through the pain, your body and mind adapt once you make a habit of it: you stop dreading it so much and you get less sore afterwards, even while you start upping the difficulty on your rotations. It's all momentum.