In my opinion the main problem with having a hard time motivating yourself to work on a project is the simple fact that subconsciously we don't really feel pass

In my opinion the main problem with having a hard time motivating yourself to work on a project is the simple fact that subconsciously we don't really feel passionate about it - from the technical point, the problem it solves or the niche it's intended for. Why not take a step back and think if this project is really important to you and something you'd like to work on for the next X months/years, maybe you do it only because you want to learn new technology, or you hope it will make a lot of money, or you want to create something related to your passion, but the project itself is boring, or you feel it's the "future", but not your kind of future. You could read dozen of books, take motivational courses, practive meditation and so on, but if you aren't really, REALLY passionate about the thing you want to create, you'll need to push yourself over and over again, until you get burned out.