If something enervates you, it makes you very tired and weak—almost to the point of collapse.
If something unnerves you, it makes you upset or nervous; it can also make you lose your courage because it frightens you so much.
get ready for something difficult or unpleasant
marked by calm self-control (especially in trying circumstances)
unpredictably excitable (especially of horses)
the anxious feeling you have when you have the jitters
being in a tense state
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