"Inspiration isn't something you can schedule, harness or control. Inspiration is more like food poisoning: it sprays out uncontrollablly when you need it the least." -- The Oatmeal
That's why we sleep with notebooks by our beds, after all. We often think best when we're not trying to think, like while dreaming or standing in the shower. But that's kind of what makes inspiration great: it's a surprise.
Making Things [The Oatmeal]