I regularly talk to people who say they want to write a book. Each is in a different place relative to beginning, fro vague idea to outline. It's intimidating even to those who had write "long papers" in school. Writing a unique book in any genre has little in common with structured academic assignments. I remind them that writing a page a day for a year, generously edited down, can yield a decent book. The trick is to structure the book well, which can be learned from an experienced published author. If you're thinking about writing a book, if nothing more than the process, do it.