Haruki Murakami, What I Talk About When I Talk About Running, translated by Philip Gabriel (New York: Alfred A. Knopf, 2008; 2007), p. 79-80:
Writing novels, to me, is basically a kind of manual labor. Writing itself is mental labor, but finishing an entire book is closer to manual labor. It doesn’t involve heavy lifting, running fast, or leaping high. Most people, though, only see the surface reality of writing and think of writers as involved in quiet, intellectual work done in their study. If you have the strength to lift a coffee cup, they figure, you can write a novel. But once you try your hand at it, you soon find that it isn’t as peaceful a job as it seems. The whole process—sitting at your desk, focusing your mind like a laser beam, imagining something out of a blank horizon, creating a story, selecting the right words, one by one, keeping the whole flow of the story on track—requires far more energy, over a long period, than most people ever imagine. You might not move your body around, but there’s grueling, labor going on inside you. Everybody uses their mind when they think. But a writer puts on an outfit called narrative and thinks with his entire being; and for the novelist that process requires putting into play all your physical reserve, often to the point of overexertion.