From "You and Your Research" by Richard Hamming (discussed at http://news.ycombinator.com/item?id=229067) :

    Most great scientists know many important problems.
    They have something between 10 and 20 important
    problems for which they are looking for an attack.
    And when they see a new idea come up, one hears them
    say "Well that bears on this problem." They drop all
    the other things and get after it.

    ...

    The great scientists, when an opportunity opens up,
    get after it and they pursue it. They drop all other
    things. They get rid of other things and they get
    after an idea because they had already thought the
    thing through. Their minds are prepared; they see
    the opportunity and they go after it. Now of course
    lots of times it doesn't work out, but you don't have
    to hit many of them to do some great science. It's
    kind of easy. One of the chief tricks is to live a
    long time!