Rob Dial argues that trying to solve life's problems in your head is like doing complex math mentally. Writing things down externalizes your thoughts, brings unconscious patterns into awareness, and makes problems easier to understand and act on.
Chapters
If I were to say what's four plus three you'd go seven but if I were to say what's 496 plus 3814 you might be able to figure out in your head but if I said what would be an easier way for you to figure it out? You go do you have pen and paper? That's for a little bit more of a complex math problem. You have your entire life, you have all of the things that's ever happened to you. You have every relationship you have all of these feelings around somebody and you're telling me that that's less complex than trying to figure out an addition problem? Why do you try to figure out your entire life in your head? Head? There's so many things dancing around all the time. There's emotions, there's feelings, there's your past. There's mostly things that you're unconscious of that you're trying to bring to the your conscious awareness. If you put it on paper it becomes easier.