From Anthony Pacheco, Hack writer:
"A lack of self-esteem will hork (and hork is a technical term) writing. It is an automatic fail. If a writer sits around thinking of perceptions of what people think of her, how she is or was treated, or other such deviations from the core of her center (and they are deviations), she is wasting time putting words to paper and wasting time showing them to other people."
and more words of wisdom:
"If you fail to get an agent, forget about how that makes you feel. Do you want to finish the book you are writing on, indeed, must finish it because it is a burning need? Yes? Congratulations. You are a writer. Your passion for writing is boundless. You are an artist comfortable with her craft. Writing is what you do for fun. It is enjoyable. Someday you may see your book in print, but then again not.
If there is no passion at this fork in the road to continue, simply take an objective look—do you feel like you are wasting your time? Is something more interesting to you? If so, writing is probably not your thing. Go find your thing.
But if you simply don’t want to go on because you are afraid that you’ll get rejected yet again—but the passion to write is still there—you have problems. Your problem could be your writing sucks. And well, we can all learn to be better writers. That problem is fixable and by the continuation of writing, you can improve."
OK, pretty lame of me to quote someone else's blog post so extensively, but what the heck. Thanks, Anthony.