I've got this John Wayne quote on mugs, t-shirts, wall plaques, and notebooks. It's always been my favorite, although until recently I hadn't given much thought to how much it fits with what a writer does.
Writers are almost always scared to death. They're scared to death no one will like what they write. They're scared to death they won't get their work published. Then when it is published they're scared to death it won't sell, or if it does, people won't like it. Then they start worrying about the next story, or essay, or book and they go through the whole process again; scared to death no one will like it, it won't sell and when it does, no one will buy it. The circle of fear, writing, publishing, fear, writing, publishing...it just keeps going. So although we are always scared to death it will all end at any minute, we still get into that saddle and write the next story or novel or screenplay. We will always saddle up and write.