Before I begin writing a new story, I'm full of ideas. Bits of dialogue, scenes, and plotting craziness are scribbled on scraps of paper and Post-its, and stuffed into random text files and word docs on my desktop. There are so many of them that of course they'll easily make a Whole. New. Novel. Or, er, a couple of chapters.
While I agree with Twain that getting started is oh-so-important... getting started (for me) isn't usually the problem. Continuing is the problem.
I don't believe in writer's block the same way I don't believe in morning sickness. That is to say, I don't believe in it until I have it. And when I finally do get the comeuppance of having it, then it's all, "Well, shit," and scrambling to remember all that stuff I'm supposed to do to make it go away.
I know what causes my writer's block. Sure I do. It's my Inner Editor. She is a raving lunatic perfectionist, and she's never happy. Never. Happy. After I click publish, I will find errors in this post and wonder why I bothered writing it. The temptation is to freeze. I've done that before. I did that for years. The difference between the Tammara who never gets ahead and the Tammara who does is simple: I will click publish on this post, with all of its imperfections.
Then, I'll march back into my Writer's Cave and gag my Inner Editor, and/or hand her tequila shots until she shuts up. ;)