The simple answer is: because writing is nothing more than making lots and lots of decisions.
Think about it. First you decide you want to write, either because you have come up with a great idea or simply because you enjoy the written word. Then you have to decide to make time to write and how you're going to write: computer or pencil and paper, or perhaps out loud into an audio recorder.
Once you're sitting down facing that blank screen or page then the hard work starts. Some decisions you may have made mentally while brainstorming your idea, but most others will happen while you are actually writing. Whose point of view is the story from? What tense will it be in? What is the setting or time period? Who are the characters? What are they like? What do they want? Is there conflict? What is their individual vernaculars? What words do I choose to use to describe? What if the plot goes this way - no wait, what if it went in the opposite direction?
Every moment of writing is decision making and that is what makes it hard. Unless you've brainstormed a lot mentally, it's not going to be easy to just start writing and knock off a hundred pages in a day. In fact, even with all your prior preparation, you're going to find that putting those images and scenes down in actual writing isn't as glib or smooth as you thought it would be. New ideas will sometimes bombard you, changing the course of what you've previously decided. Characters won't behave the way you originally envisioned. And sometimes you write yourself into a corner and get stuck. Getting unstuck can utilize some of the hardest decisions. It may mean cutting out a lot of what you've already written to go in a new direction. Or perhaps you need to decide to do some research to help solve the problem your characters are facing.
Character A is on one path, should they collide with Character B? When, if at all? How will the arcs of both these characters affect each other? How much action versus explanation should go into this scene? Do Characters C and D hate each other? Do they secretly love each other? Will the fate of Character E end in death? Will the villain win? Is there an identifiable villain? Decisions.
There is an accountability to writing. A law of the universe not often discussed is that for every decision made there are consequences. For your characters, and yes, even for you as the writer. Decisions about the words we use may either draw readers to our work or push them away. The point of view we choose will often determine our target audience. What elements we choose to put into the story will also draw or repel readers. Whether or not we choose to get feedback and improve our writing can have some very powerful consequences over how successful our novels may be.
It is not a mere moment of deciding "I am going to write a story today," although that is always a starting point. We can just as easily decide "This is too hard; I'm going to quit." Once you are determined to set down the winding path of writing a story, you will stop frequently - more often than you'd like - to assess, rethink, and choose. It's not a path for the fainthearted or lazy.
After you've crossed the finish line on your first draft then comes the next big decision: "I am going to go through it and rewrite it, edit it, and improve it." Subsequent drafts of editing and revision require even more decisions, some of them painful. Deciding to get feedback from others in order to improve your story has powerful consequences at well. Ideally, you should be given sound advice from people who read a lot and know a thing or two about writing and editing. Sometimes the feedback is unhelpful. You have to decide who to listen to. You have to decide which advice will make your story better and then choose to make the appropriate changes.
You choose if you want to go after publication or not. You choose which publication route you want to take. If going the traditional route, you have to choose your words carefully for a query letter and choose which agents and publishers you are going to solicit. You have to choose whether to keep going that route as rejections come in. And hopefully you'll get to choose who'll you'll work with and help make decisions in the publication of your novel. If you choose the indie route, you have even more decisions to make. Who will your printer service be? What format(s) will you publish in? Who do you get for cover artwork or do you do it yourself? You need to choose good editors and copy editors. You have to choose fonts and layout. And with either route there's all the marketing choices you'll have to make to let people know about your book.
And then you have to choose whether or not you will start all over with a new novel.
Writing isn't some blow-in-the-wind hobby, not if you're serious about it. Writing takes decision-making skills and lots of determination. Many people have taken up writing this month for fun. For those new to the game, you're probably finding out it's not so easy as you probably thought. I would hope that by trying it out, you'd gain a better appreciation for the books you've read and those determined people who have moved forward by the hundred thousands to make decision after decision to create the stories you read and love.
And for those of you who are not new to the game, I share your frustration and joy of the process. The hours seem to slip by so quickly and yet so little seems to make it to the page. I believe at least 75% of our writing time is spent up in our heads making decisions.
This is why NaNo's word count is a true challenge for those taking it seriously. Writing is hard.
