I work on a day by day basis, rather than breaking out the whole month. I make my list for the day, and if I complete the list then I get to play a game, or read a book, or watch videos, or whatever. I would certainly count that as motivation.
Perhaps you aren't looking for motivation though. Not in the sense of "something that pushes you to do your work." Maybe you're looking for focus and drive, the ability to keep your attention on your game rather than flit off towards a million other projects and ideas. - In which case, that's a very personal thing and depends on the person. Both for WHY it might be hard to do something and ways to help make it better.
Like, in my own case, I used to be very bad about finishing projects to the end. I would always get distracted and hop to another thing part ways. It wasn't that I lacked motivation - I just lacked focus and an attention span. It was through a desire to overcome what I viewed as a flaw that I learned to see things through and dedicate myself to them.