“A person’s fears are lighter when the danger is at hand”

This quote from Seneca describes how often we are more worried or fearful about something coming than we are when we actually face it. This is because when we actually face whatever it is that has us distressed, we don’t have as much time to dwell on it and let negative thoughts come into our mind.
Think about when you are preparing for an important interview or test. The fact that an important interaction is coming up weighs on your mind, and you begin to feel tense. You keep thinking about it and dread it.
But then the moment you start your test or your interview, this feeling usually fades. Your mind goes from dreading to reacting. There is probably a scientific explanation for how your brain switches from nervous anticipation to fight or flight mode, and how the latter doesn’t leave space for the former in your brain.
Whatever the scientific or psychological explanation, when you are finished with the test/interview/encounter, you might look back and marvel at how much more nervous and fearful you were before the thing you had to do than you were actually doing it.
Now, in a sense, this is natural. It doesn’t mean that if, after recognizing this, you continue to be more apprehensive before a test or interview than during it, you are doing something wrong. A part of it is natural. But you can take this knowledge as a way to slightly ease your anxiety before another test. Tell yourself “I’ve done this before, and the anticipation is almost always worse than actually doing it.”
It’s not going to make you go from extremely nervous before a test or interview, to completely serene before it. But it can be a step towards easing your nerves little by little. At some point, you might be a little nervous before these situations, but nowhere near as fearful as you used to be.
This can also be a lesson that your own mind puts you through more distress than most things. If you can recognize this and slowly minimize it, you will be saving yourself from a lot of unnecessary fear and stress.
Understand this, prepare, and do your best when you are in the situation. That is all you can do, all you need to do, and you will be better off for it.