try thought disputing, replace you negative thought with exactly opposite one, focus more on your present and set task lists for the day.

You have to stay positive and work hard

Do things anyway. Even if you think it'll end up in worse, do it if you think what you going to do is right. I mean, if you are afraid you can't pass an exam, study as well as you can don't think of result. Then you can say that youbdid what you can even if you don't score well. But if it is something like lie to your parents and do something against their good wish, that you know is wrong, don't do that. 😁 I hope it is clear. Do your best and leave the rest. Atleast you can say to tried your level best.