Changing your thinking is possible, because most of how you and I think boils down to simple habit. We react to certain life events the same way because…that's the way we've always reacted. It's familiar. Fortunately and unfortunately, our brains were designed to be efficient. It's simply faster if I learn that touching a hot stove means a lot of pain and develop the "habit" of avoiding the thing the next hundred times I'm frying an egg than to have to stop and think, "Wait, let's reason this through. Should I touch it?" That's the "fortunate" side. The unfortunate side is sometimes the way we reacted to a life event created a self-defeating thought or belief that is actually no longer good for me.
Let me give you an example. A child on the first day of class is embarrassed when the class makes fun of him for wearing last year's jeans. This devastates him, because all he wanted to do was fit in and not be "odd." From that day on, to protect himself the child begins to predict what people are thinking about him, so he'll be prepared for the worst just in case it happens. That's called "mind-reading." Ever done that before? The problem with that is that it introduces the thought: "Something might be wrong with me." And from there, it's only a hop, skip and a jump until you start believing that there really is. Mind-reading, however, is actually fiction, a completely made up story-a game the child plays to try to avoid being hurt: "Why are they looking at me today? Is something wrong with me?"
What should happen is someone should have a conversation with him, find out that he's trying to be a mind-reader, and prove to him that it's only a game he's playing with himself. Someone should have asked the child, "OK, if you're a mind-reader, then what number am I thinking of? Or who's going to win the Super Bowl?" A thousand bucks says he'll get it wrong. Adults play these thought games, too. Our thoughts were never challenged, so we still play them. The only difference is we got a little bit taller and a little bit older. In therapy other self-defeating thoughts and beliefs should be identified and if necessary, challenged and changed.