I meet many people who want to write a book. It’s a dream to be a published author. The challenge is to develop the discipline to write on a consistent basis.
You can discover what your book should be about by making a list about what you are passionate about. What do you enjoy doing? What do you look forward to? If you think about retiring what would you choose to spend your time doing?
Ask friends what they believe you are good at doing. Many times your friends have great insights into how they see your accomplishments and skills.