It is said that “Inside everyone there is a book.” The big problem is getting it out! All books start with an idea. With non-fiction it is usually a concept or a message waiting to be communicated. With fiction it is a story wanting to be told. Either way, the idea eventually germinates into a fully-fledged project.
Everyone has a story. All have experienced life with its joys and trials. Every family has a history and these are the places to start. Like me, it may be that those stories will just be used to illustrate principles or add realism to your writing.
Whatever you write it will always take three things, diligence, discipline and determination. It will take diligence in your planning, discipline in getting pen to paper and determination to remain sufficiently motivated to stick with it.
I have several friends who have ideas for books. Their next step is to start writing. Remember the old saying which is supposedly Chinese, “A journey of a thousand miles begins with the first step!” If you have the desire, and you have an idea, why not get writing?