Some practical, yet very useful advice from Chris Baty, founder of NaNoWriMo:
1) Write every day. Even if you just knock out 75 words before collapsing into bed, those 75 words will keep you connected you to your story in essential ways, and make diving back into your book much easier.
2) For now, stop thinking about 50K. Just sprint thousands. Visualize each writing session as a tall staircase made up of 1000 steps. You are part ninja, part monkey, and part stairmaster cyborg. You were born to fly up those steps. Bash out 250 words, and you've made it halfway to 500. Keep going for another ten minutes, and you're past 500 and within striking distance of 750. Once you hit 750, you could sneeze out enough words to get to the top! After each thousand, be sure to take a quick break and celebrate. Then fire up that monkey spirit and go run another thousand.
3) Remember that your book is important. I didn't say this in the Week One pep talk because we'd only just met and there's really only so much cornball sentiment from a random guy on the internet that anyone should have to tolerate in one month. But here's the truth: You have a book in you that only you can write. Your story matters. Your voice matters. The world will be richer for you seeing this crazy creative escapade through to 50,000 words.
Well, I've made it past the 20,000 mark which was the goal for all writers to reach by 12/11, so I'm a little ahead, for now!