Tune in to positive emotions. If you are suddenly visited by a negative thought, chase it away. Try to catch yourself in that thought and deliberately think about the opposite, positive point. Say mentally: "No, that's not gonna happen", "This cannot happen", "I'll be fine" and so on.
Possibly, more load yourself with all kinds of business and occupations, there was no time to think about the bad. The lack of time for all sorts of negative mental demagoguery will significantly reduce the level of anxiety and negative self-hypnosis.
Purposefully teach myself good, trying to find a real reason. For example, you go to the exam. Do not think that you do not pass it, you will have "unsatisfactory" and so on. On the contrary, mentally tune into a favorable outcome and justify it. "Because you learned the material the day and night! Why you should not pass?" or "Yes, I learned partially or completely. But either gets a good ticket, or give the opportunity to retake the next time. But all will end happily!"
Focused self-hypnosis positive result must be accompanied by real actions to achieve it. Do not sit idly by.
Once the goal is achieved, be sure to mark this mentally as their achievement, even if it's a minor success. According to this approach, negative thoughts will come less and less, as if suddenly this happens, it is from a single reflection will be easy to get rid of. Most importantly, the steps outlined below will help to get rid of auto-suggestion, which systematically interferes with the normal life and achieve their goals.