There's a fairly old post from the I Should Be Writing blog that I wanted to link, called Appropriate Questions To Ask Oneself While Writing. I love this post because it really helps remind me of the mindset it takes to get through the drafts of a work, and I thought it might benefit others. (Also, posting it here means I don't have to hunt it down next time I need it.)
1st Draft: What happens next?
This is the only question you should be asking yourself as you write your first draft. The. Only. Question.
The point of the first draft is the foundation, the rocks you build your story on. And for that story to be built, the foundation has to be finished. Nothing is more important in writing your first draft than reaching the end. Not your word choice, not your plot mechanics, not your personal politics. All of that can be changed, but not until the draft is finished. This means when you're done you'll have a pretty shitty piece of writing, but who cares? You've got at least 3 more passes to get it right.