Once what you had in mind to do gets done, you have to channel it, double-quick, into something else, or else it starts giving you all kinds of insane ideas...most of which sound perfectly plausible at the time. And if you don't watch out, you'll do something really dumb.
For instance, I just snapped myself back into focus, when I realized I was wandering around the house, looking for a tape measure, because I wanted to see how big a window I could case-mod into the Banshee, and had already started searching the web for laser-cut fan grills.
That was a close one.