May I ask how you started out with the book? How did you come up with the structure and content. It seems to me that it is relatively easy to hammer out just a

May I ask how you started out with the book? How did you come up with the structure and content. It seems to me that it is relatively easy to hammer out just a book to have a book. For a memoir or something like that this might be fine. But writing good quality practice/problem centric ones with cases, illustrations, and a decent layouting appear to me like demanding an incredible amount of work. Would be very interested in any thoughts on how to optimize this process.