Thinking errors are statements we tell ourselves that are not true and/or based in emotion. If you're human, it is likely you will have at least one thinking error. We are programmed from birth to listen to the "shoulds" and "always" and "nevers." It seems to me that two particular thinking errors trip up writers, or any other person who wants to share their art with the world.
The first is the notion that "I know what you are thinking, and it isn't good." In everyday life, it's when you walk into a room, perceive everyone is looking at you, and decide that they must be thinking your new haircut looks stupid. For a writer, it's the nasty voice living in your head, telling you that you might as well give up because no editor, publisher or agent will ever think your work is good. It's why rejections are so tough - and form rejections even tougher. They leave more room open for Nasty Voice to say "If the story was anywhere near good-enough, they would have said something."
The second is "I know the future, and it is sure to be bad/good." Tricky, this one. It has two sides. My demon is the first. Nasty Voice says, "I don't know why you're wasting your time. Look at your kids over there, all happy-but you still aren't playing with them. Don't you know how tortured they are going to be when they grow up because you wasted all that time writing instead of being right by their side. You'll never get someone to publish/buy/read your story, anyway. So you might as well quit." Talk about robbing the writing process of it's fun.
The other side, where the writer is convinced the future is good, can create complacency and foster an "I am the Writer" type of attitude. The writer doesn't need to learn or work, because they know it all, already. In a highly competitive field, that is career suicide. It also leads to a rotten attitude that puts others off.
What to do? The first thing we have to do is identify that we have "stinkin' thinkin'." We have to recognize that the whole writerly world is not out to get us, and hold us down. And then, we have to look for the facts. This is where goal setting is helpful. By creating attainable goals, and reaching them, we have something tangible to show Nasty Voice when it starts flapping it's gums.
One more thing -- we have to talk back. We have to get an attitude and tell Nasty Voice that it doesn't know everything.
We work hard.
We remind ourselves our chances of having our stories published are as good as anyone else's. And, we just keep writing.