“I stop working when I start making mistakes. Typos and misspellings tell me I’m tired. I have reached the point of diminishing returns. Steinbeck said he always wanted to leave something in the well for tomorrow. Hemingway believed you should stop when you knew what was going to happen next in the story. You and I, as writers and artists, are playing always for tomorrow. Our game is the long game. When you’re tired, stop.”

Steven Pressfield, Put Your Ass Where Your Heart Wants To Be (Page 78)