I've been reading writers' 2007 writing goals on various discussion groups and blogs, and what each writer wrote was revealing. I'd take a $100 bet anytime on which writers achieve their goals, and which do not.
What you say to yourself (and others) is vitally important to your success. The writers who won't succeed were beaten in their own minds already.
Dodo words, and no task list or specific time line
The writers who doubted themselves were easy to spot. They sounded tentative... as though their goals for 2007 were nice dreams. They used dodo words like "plan", "try", "aim", and "think". (By "dodo" I mean dead words.)
They "aimed" to "try" this or that market, or would "try" to write such and such.
They were beaten already. No offense to the writers. They were all new. From their voice, I estimate that they were all in the first three years of their writing careers. Writing is such a complex endeavor, no matter what you write, and there's so much to learn, that this tentative approach is completely understandable. If you don't KNOW, you don't know, right? You can only "try".
Wrong. You never try, you DO.
The most worrying aspect of these writers' goals was the tone of defeat. You can't win if you beat yourself! More to the point, if you REFUSE to even consider defeat, no one can beat you. (Viz the Australian cricket team and the prospective Ashes whitewash.)
I started my "real" writing career with a bang. I decided at age 29, that since I was selling my writing here and there, I could make a success of writing if I put some effort into the process. So I did. I gave myself until I was 40 to do it. I did it (sold a series of romance novels) in ten months.
I had a considerable amount of CONTEMPT for that goal.
It wasn't a matter of "trying" anything. It was a matter of planting my butt in a chair and DOING it. So I did.
Create goals with a task list and time line
To ensure success, you must translate your goals into specific tasks, and enter those tasks into your diary. See my post on how to "do goals" in Fab Freelance Writing.