Snagged from wesha...
If you want to be a writer, write. You may have to get a day job to keep body and soul together (I cheated, and got a writing job, or lots of them, to feed me and pay the rent). If you aren't going to be a writer, then go and be something else. It's not a god-given calling. There's nothing holy or magic about it. It's a craft that mostly involves a lot of work, most of it spent sitting making stuff up and writing it down, and trying to make what you have made up and written down somehow better.
I think for me the tipping point was when I was a very young man. It was late at night, and I was lying in bed, and I thought, as I often thought, "I could be a writer. It's what I want to be. I think it's what I am." And then I imagined myself in my eighties, possibly even on my deathbed, thinking that same thought, in a life when I'd never written anything. And I'd be an old man, with my life behind me, still telling myself I was really a writer -- and I would never know if I was kidding myself or not.