While you can never guarantee the outcome of a race, you can create the same effect in your mind by simply making the outcome irrelevant.
It’s something you sometimes hear people say every now and then:
“Being nervous before a race is great! It’s a good thing! You should be nervous before you race!”
I’m going to come out hot here straight from the beginning – Nervousness is NOT good for swimming. While there are some small benefits to feeling nervous before a race, those benefits are far out-weighed by the negative side-effects. For example, sure, you’ll experience an increase in adrenaline by being in a nervous state. However, one of the negative side-effects and physiological reactions of being in a state of nervousness is that your body tightens up and your muscles become tense.