What do you work on?

You should work on, first and foremost, difficult challenges.

Don't care too much about prestige:

Prestige is just fossilized inspiration. If you do anything well enough, you'll make it prestigious. Plenty of things we now consider prestigious were anything but at first. Jazz comes to mind—though almost any established art form would do. So just do what you like, and let prestige take care of itself. - Paul Graham

How do you work?

In my experience, work is easiest and most productive when you're interested in a problem. This makes todo lists hard to follow, since you'll see a list of complicated tasks rather than interesting problems to solve. One way you could combat that is by reading a task and thinking about the vision behind it - consider the intricacies, purpose, and meaning.