You've got to work on important problems.

Richard Hamming "You and Your Research",
Transcription of the Bell Communications Research Colloquium Seminar, 7 March 1986
http://www.cs.virginia.edu/~robins/YouAndYourResearch.html

... And I started asking, "What are the important problems of your field?" And after a week or so, "What important problems are you working on?" And after some more time I came in one day and said, "If what you are doing is not important, and if you don't think it is going to lead to something important, why are you at Bell Labs working on it?" ...

... If you do not work on an important problem, it's unlikely you'll do important work. It's perfectly obvious.

Good and Bad Procrastination, December 2005, Paul Graham
http://paulgraham.com/procrastination.html

There are three variants of procrastination, depending on what you do instead of working on something: you could work on (a) nothing, (b) something less important, or (c) something more important. That last type, I'd argue, is good rocrastination.

Good procrastination is avoiding errands to do real work.
Good in a sense, at least. The people who want you to do the errands won't think it's good.

In his famous essay You and Your Research (which I recommend to anyone ambitious, no matter what they're working on),

Richard Hamming suggests that you ask yourself three questions:
- What are the most important problems in your field?
- Are you working on one of them?
- Why not?

What's the best thing you could be working on, and why aren't you?