Is it possible to stop imagining the worst outcomes of every situation?

There is a saying called "Do for the best and prepare for the worst". This thinking is not wrong but if you keep thinking all the things with worst outcomes and you will see things in a negative way. So this is different. Please give your best whatever you do with the right attitude. Even the result isn't good enough and you don't have anything to regret. You did your best with all you could. What matters the most in the end is that you need to learn from your mistakes and not repeating same mistake in life. Let's say you think you have sit an exam very well but not getting full marks as you expected. Then you realised that you skipped one last question at last page of exam paper. It shows you can be little bit careless to check all pages of exam papers. Then make sure this similar case doesn't happen again.

Yes. When you start talking and getting the help you start to look into the positives more than the negatives. Talking it out and realizing you are never alone is the first step to turning your thoughts around. I know from expierence that working on your mental attitude will help you complete other goals in life and be more successful overall. Just don't ever give up on yourself because the toughest battles will always be the ones you have in your own mind. Just remember your calming methods and try to see the bigger picture in every situation. You are doing great.

It is very easy and normal to imagine the worst possible outcome of every scenario. Sorry to hear you’re having to go through that, it can take a heavy toll. I think we’ve all been there with our negative filtering and our all-or-nothing thinking. A trick I use is called “bridge statements”. These are statements which we can apply to any thought suggesting that maybe our thought may not be true. For example a thought you may have is “I’m going to fail this test and score a 0”. A bridge statement may be, “it is...maybe possible that I may not absolutely fail this test. Maybe I will score some points. Possibly. Could happen.” The concept of bridge statements allow us to open up to the possibility that our thoughts might be wrong. At the end of the day, as Kati Morton says, thoughts are just thoughts. They are biased opinions.