Thinking about what books to write can be a difficult process. It’s not so much that ideas are hard to find, it’s that there are so many of them. Each idea requires a lot of time and energy. So the difficulty in writing really is in figuring out which ideas are worth writing about. One way to help determine this, is to sit on an idea. If the idea survives or even weeks, then you know it has potential to be a good idea to write about.