Creativity is a force far greater than you or I. The only thing we know for sure about the force behind the universe (call it what you will) is that it is creative. Each leaf, each snowflake, each hair on your niece's head, the pen in your hand, is a creation. There is infinite creative power. That means you can have some. Actually you can have as much as you want, it's everywhere, and it won't run out.
When you draft, quit trying to sit on or control the creativity coming through you. Give up some control. Be an open faucet. Let your first drafts flow and freewheel. Don't censor, don't judge; trust the process. Poet John Keats called this state of receptivity "Negative Capability" -- "when man is capable of being in uncertainties, Mysteries, doubts, without any irritable reaching after fact & reason." Being a poet, or any kind of artist, requires some level of receptivity, of trust, the same kind you had as a child.
Let the first draft be long, breathy, sloppy, the "discovery draft," the "big bang." Of course it is not the final draft and never will be. It's raw material which will require conscious shaping and crafting -- and openness to creativity as you revise. We all know an Edgar Allan Poe work when we read one. He wasn't intimidated by his own (weird) creativity. He had the skills to handle it and give it shape. Whether you enjoy it or not, his work isn't incoherent or shapeless. His skills gave him the confidence to offer his creative work to the rest of us.