How to write a book  from start to finish without agonizing over the process: List 3 subjects or themes that really interest you. Think about each of them for 3 days and on day 3 choose what to write about and stick to it. Create a writing plan in 3 days. Take 3 days off to prepare to write mentally and emotionally.

Start writing on the following Monday. Write Monday through Friday (5 days a week). Give yourself 3 months to complete the first draft.

Put the book aside for 3 weeks. After 3 weeks, revise, edit and proof for 3 months.  

Next, send the manuscript a qualified editor if within your budget, otherwise, let a fellow writing buddy review your manuscript (you can review her book as payment). Last, but not least, submit for publication or self-publish.

Start a new book.