Frank Chimero:

Ideas are a son of a bitch like that, because they always come when you are least prepared to preserve them. Inspiration is like some sort of weird collision, where the idea is always sweeping across the landscape, through the neighborhood, or in and out the bedroom window. For that idea to hit you, you must be moving as well. If you’re standing still, the idea will whip right around you and keep going. It is like some sort of weird reverse game of chicken, where the sole way to make contact is by trying to miss one another. The only other things with the perfect and unfortunate timing of good ideas are the internal clocks of long-forgotten ex’s that tells them to appear everywhere during the first couple weeks of a new relationship.  

 Chimero’s book The Shape of Design is a must-read.