As of late, I have found a mindset that is enabling me to get more done on my current project, and I've decided to share it.
The mindset is this: any and all time spent on your project is progress towards it being finished.
Life is busy, and there's a ton of stuff pretty much all of us HAVE to do. By the time we've done all that, it can be extremely difficult to find the time and/or energy make progress on a side project.
I am a person who has often chosen "procrastination" over making progress on whatever I'm working on. But I have found lately, by remembering the above, I am more motivated to choose working on my project instead.
If I do nothing, I've made no progress. But if I do 10 minutes work on my project in an evening, I'm 10 minutes closer to it being finished than I was before.
And it's not unusual for telling myself I'll do 10 minutes to turn into enjoying working on it again, and that 10 minutes turning into an hour or a day, or several days! It doesn't always happen. When it doesn't, well hey I made 10 minutes progress. When it does, great, I'm on a roll again!
Additionally, remember it doesn't matter if you spend a week working on your project only to realise you've completely messed up, and the entire week's work needs to be thrown away. You have still made progress, because no matter when you started, that would have happened anyway. And the sooner you go through that process, the sooner it's out of the way, the less total time you have left until the project is finished.
The reason I mention this, is because sometimes the concept of doing some work just for it to potentially be a "waste" can put us off making a start. Make that start! As per above, it's still progress.
Any time you're working on your project, you're also engaged with it and thinking about how it works. Which means you're more likely to continue the next day while you're still thinking about it.
Additionally, "light" engagement with your project is better than none at all. If you're feeling a bit overwhelmed by your project's todo list (be that a mental one or an actual one), just fire up the project, find literally anything to do and do it. If it's a programming project, looking through and adding helpful comments to your code is better than not firing up your project at all. Or pick the very easiest thing on your todo list and do it. Or organise some code. I often find starting this way leads to actually getting the important stuff done.
I am not claiming at all to be any kind of expert on motivation. I'm not saying you should be spending your entire spare time working on your project. I'm not even saying this advice will work forever.
I am just saying lately the above has helped me get back on with it at times where before perhaps I wouldn't have before. Maybe it will help you too.