There is one bit of encouragement that I will never forget. I was in high school and we were given a homework assignment to write a pro or con argument for why students should be required to recite the Pledge of Allegiance in school. I was assigned the con position, and when I got home I quickly dashed off an adequate paper to turn in the next day. Then I reconsidered, and went back and rewrote the paper, making an impassioned case for why we should have the freedom to remain silent during the pledge (not necessarily my opinion, but I used the emotionally charged nature of the subject to make a strong case nevertheless).
The following day toward the end of class the teacher was remarking on some of the homework papers, what she liked about this one or that one. Then she said "I want to read you something." I turned beet red when I realized that it was my paper that the was reading aloud to the class. The entire class was dead silent as she read, then she said, "That's just an example of what you can do if you want to put some more effort into your work."
I felt self-conscious, but very powerful. That was my first experience where I felt that I could move people with my words. I think that changed my whole attitude toward writing.