In my previous post, I gave the most basic key to survival. It's certainly a good one, but I didn't relate it to writing directly enough. So I'm fixing that now.
As a writer, you're gonna write some lousy stuff. You're also going to write some good stuff. But either way, you're going to get your heart broken. Somebody is going to say the worst, most hurtful things imaginable to you. You may feel inclined to pack up and turn away, never to come back to writing. Don't do it. Don't give up (unless you have truly lost all of your passion or desire). The only way to survive that kind of heart break is to not die. Keep on writing. That's the only way to survive as a writer.