Dream big. If you don't think you can do it, you won't. Have you ever heard about the power of positive thinking? You might not believe that this works, but it's better than negative thinking. The Bible clearly states that words have power and you live what you think. So if you are always thinking bad thoughts about your life and your writing, things will not turn out good.
Also, I've heard many people say over the years that it is healthy to daydream about the way you want your life to be. Most people can't think out of the box. They will picture what they think is great success, but it is just a small fraction of what they could actually have if they applied themselves. It makes sense to me. If you are going to dream, dream big.
That's all I'm saying. Happy writing! :)