A point of clarification, with the Bearded iris lady in mind. By saying that one is not required to produce a book before one dies, I am by no means saying one should not do so if one wants to. By all means write a book, write ten books, I shall be very happy for you.
But when a person exhibits clear avoidance behavior, doing pretty much anything but the task at hand (ie, writing a book), I can think of only two solutions. One is to force matters and sit down and write. The other is to recognize that producing a book does not define you as a person. You have an interesting and productive life, one element of which is already writing. You could assemble an interesting book from your gardening columns if you wish, but your goal is the novel.
If you are asking, How do I force myself to sit down and write, that is not a question I am qualified to answer. When I began writing, I did so because I loved the process of building a novel, and never felt the need to force myself to proceed. Fifteen years on, there are times when I have to make myself stop fussing with closets and web sites, gather my thoughts, and put words on a page, but even now, when writing is inextricably linked with mortgage payments and looming deadlines, the frustration of an unfinished story is still the greater motivating factor.
Speaking objectively, you do not need to write a book to get a passing grade in life.
Speaking subjectively, from within yourself, this may not be true. You may feel so strongly that there is a book that needs to come out that if you don’e2’80’99t write it, you have somehow failed.
If that is so, all I can say is, you need somehow to overcome those avoidance activities that are distracting you. You need to require yourself to produce one page every single day of the next year until that book is finished, and not get dressed or have lunch or check your email or whatever goal you set yourself until that page is in the world. It may be rubbish and shapeless–my first drafts invariably are–but it exists, as it did not exist when you woke up that morning.
You ARE a writer. You WANT to be a novelist. But the hard truth is, the only way to do it is one page at a time.
And–good luck, all you future novelists out there.