Frustrated

It's so frustrating that I cannot write no matter how much I want to. I figure that an aspiring author should be writing nonstop, writing constantly, always working on some project or another. But I cannot write anything. Nothing. I try and I try to write a story or a poem or just a blog post and nothing comes out. And if something emerges, it's bound to be a load of shit. It's just so frustrating because I want to be an author; I want to write for a living, create worlds that people want to visit. But I can't even type a single sentence.