"Opportunities that present themselves to you are the consequence -- at least partially -- of being in the right place at the right time. They tend to present themselves when you're not expecting it -- and often when you are engaged in other activities that would seem to preclude you from pursuing them. And they come and go quickly -- if you don't jump all over an opportunity, someone else generally will and it will vanish."

- http://pmarchive.com/guide_to_career_planning_part1.html