[Scaevus]

I am lazy person and that's actually my internal motivation. I want to complete things as quickly as possible so that I have plenty of time to procrastinate before I start the next task.

But one thing that is crucial is to do what you love and what you are good at. Then you feel empowered and motivated to complete the task.

Also, as others have noted, sleep seems to be highly important and in that sense, besides a healthy amount of night sleep, I find power naps really helping me to get through the day.