Make the decision to become a writer and stick to it. Anything less won't be enough.
Some writers do get that one in a million lucky break. But most don't. They travel the hard way. And it can take a very long time. It took Marcus Zusak seven years.
There are many stories of success after years of rejection. Commit to being there for as long as it takes.
For me, commitment was the easy step. I didn't have a choice.
Isaac Asmov said : "I write for the same reason I breathe - because if I didn't, I would die."