Nervousness, fear, panic, low morale, low mood, low energy -- all natural things that happen from time to time.
If you go spend an immense amount of time walking and your feet feel sore, you say, "My feet feel sore right now."
But lots of times, when someone feels nervous or scared, they say, "I'm a nervous person. I'm a fearful person."
But that's not necessarily true. You don't have to identify with a given mood. Just like sore feet, worries come and go. "I feel somewhat worried at the moment" saps most of the power from it. Identifying with the negative emotion makes it stronger; noting that it's just there and fleeting makes it grow much weaker.