A habit of stopping when they’re on a roll, not when they’re stuck. Hemingway puts it thus: “You write until you come to a place where you still have your juice and know what will happen next and you stop and try to live through until the next day when you hit it again.” Arthur Miller said, “I don’t believe in draining the reservoir, do you see? I believe in getting up from the typewriter, away from it, while I still have things to say.” With the exception of Wolfgang Amadeus Mozart — who rose at 6, spent the day in a flurry of music lessons, concerts, and social engagements and often didn’t get to bed until 1 am — many would write in the morning, stop for lunch and a stroll, spend an hour or two answering letters, and knock off work by 2 or 3. “I’ve realized that somebody who’s tired and needs a rest, and goes on working all the same is a fool,” wrote Carl Jung. Or, well, a Mozart.