Ideas are slippery little suckers. One can be thrashing around in your head as if it will live forever. The next thing you know, your great aunt calls. By the time you’re off the phone, the idea has slipped the hook and you can’t remember a single wiggle of it.
[Whew… enough with the fishing analogy. I think that will be my first and final of those.]
My point is: when you have an idea, you have to catch it. (Incidentally, you should watch this Elizabeth Gilbert TED Talk for the description of the poet who felt poems coming like freight trains across the fields.) You have to write your idea down. Over at Hyperbole and a Half, Allie Brosh talks about keeping a pen in her shower, and taking a notebook on runs.
I have not resorted to either of those methods. I have, however, been known to run naked from the shower directly to the computer. My family’s quite used to it. Probably the neighbours are, too.
My point is this: ideas might be infinite. They may keep arriving like freight trains throughout your entire life and if you miss a few, well… you can always grab the next. OR, they might be finite. And if that’s the case, you don’t want to let the big one get away.