When you're stuck at a difficult part in your writing and you're just so discouraged. When you can see where you need to go but you can't figure out how to get there. When you wonder why anyone would want to read this silly thing when there are many more important items on the roster: meaningful works to be read, beautiful works, time to be spent with family, walls that need painting, a sky that needs viewing, wind that needs feeling—anything but what you're doing.
When you keep writing anyway, perhaps badly, probably slowly, because even if no one else loves it, you do. When you remember you care too much to leave it alone. And then it becomes that much closer to whole and the experience from beginning to end is so worth it.