Growth mindset is that you're always looking to improve. You see failure as opportunity. You fail your Calculus test. Instead of tearing up the paper and vowing to never look at an equation again, you actually look at what you got wrong. Instead of beating up yourself up you look at your mistakes and try to learn why you got the question wrong. Perhaps you need to talk to the teacher or study a different way. Maybe you need to spend more time studying.
When you have a growth mindset, then there is much less anxiety. If you do well then that's great. Maybe it comes easily to you and congratulations. However, you cannot wager your entire ego in succeeding immediately. If you're not perfect the first time you tee off at golf or set your hands on a violin, it is not surprising. Would you expect a baby to speak as soon as its born? Of course not. Then why do you think you should be perfect with no practice?