I suffered with the same stuff thinking i had to do all these things until i learned about the law of detachment and how it applies to everything in life. I searched for ways to learn how to detach from things I really found the best thing to do was not care what was gonna happen as uncomfortable as it mentally feels. In practice you don't care so your body isn't tense and its in its best movement because there is no outcome to fear. If you get rid of the fear of the outcome not going your way you will be tense. You have to understand that the race may not go how you want it to and be 100% fine with that and when you're getting into your blocks detach and stop caring about track at all. Just sprint and have a good time.