Throughout the entire process of learning to write, I kept hearing, "a published author is an amateur writer who didn't quit." Like most things, writing improves with practice, and one page at a time, one chapter at a time, those blank pages fill and you end up with a book-length story.
So, what have you always wanted to do? What's holding you back? Quit listening to people who say, "That's impossible," and just keep trying. It's been said a long journey begins with a single step. So take the first step and then keep moving forward. Stop listening to negative thoughts and negative people and go ahead, allow yourself to believe it's possible.