“I’m nervous” said out loud weighs less than a fake “I’m fine” carried all day.

Hiding a feeling costs energy continuously. You end up managing the nerves and also the performance of not having them, and the second job is usually the heavier one. Naming it does not remove the nerves, but it does put down the part you were carrying for the benefit of everybody watching.

Tell one person before the thing happens, in four or five words, with no explanation attached. A teammate, a friend in the same exam, whoever is nearest. Most of the time they will say they are too, which is its own small relief.