Personally:
- 5% internalized consequences
- 45% intellectual curiosity
- 50% status
I'm sort of joking. Really, I think it's that "motivation" is at least a couple things. In the grand scheme of things, I tell myself "this research is important". Then day to day, I think "I've decided to do this research, so now I should get to work". Then every once in a while, I become very unmotivated, and I think about what's actually at stake here, and also about the fact that some Very Important People I Respect tell me this is important.
My colleague Michelle wrote some related thoughts here.
https://forum.effectivealtruism.org/posts/3k4H3cyiHooTyLY6p/why-i-find-longtermism-hard-and-what-keeps-me-motivated