There are few things more satisfying to a writer than the gratification of a completed project that he or she has invested much in. To behold the finished work with satisfaction… well, there’s nothing quite like it. That’s why it’s so important to write only what you enjoy writing or would like to read yourself. Even for a short book—a novella I think they call it—there is so much time and effort and labor put in that you would be doing yourself an injustice not to. Anybody who’s sat in front of a computer screen for months on end knows what I mean.
Each and every word you write is created from within you; when you write a novel you place an amount of yourself into that novel. Imagine how horrible it would be if that amount of you was inserted into something you didn’t like! The book wouldn’t work at all. Not at all, precious. Personally, I can’t imagine spending my time creating anything I don’t thoroughly revel in. Write a great book. Write the best book out there. Just be sure that it’s a book you completely enjoy.