if you're going to change your life then you have to change it every day, not just the days the world isn't taking a shit on you, so there's no point waiting for that moment when everything will be ok and you can get started.
This is maybe the truest thing anyone ever said on this board.
To follow up on what deja says... You know, it's OK to change your mind. Just because you used to want to be something at one point doesn't mean you have to beat your head against that idea for the rest of your life. I mean, we all have lots of ideas when we were young that turn out to be not quite what we thought. You might have wanted to be a fireman when you were a kid, till you found out that it doesn't just mean riding in a big shiny truck, it also means running into burning buildings for a living. There's nothing wrong with deciding, upon mature consideration, that that's not for you.
Same thing with wanting to be a writer. It might have looked good in whatever vision you had of it, but if the reality of it makes you miserable, there are a million other things a person could do with their life. And most of them pay better and have higher odds of reasonable success. So, you know, not being a writer is really an OK thing.