Psychological and physiological response to any stimuli that an individual perceives as threatening

Stress

Explanation:  

Stress is a response to an emotional and/or physical tension, which manifests as a feeling of frustration, nervousness or anger. This feeling is "telling to the body" that any change or adjustment is needed. The body may respond to stressful situations through physiological (e.g., increased heart/breathing rate, hormone release, etc) and psychological  (e.g., anxiety, depression, etc) stress responses. People feel stress when they have the sensation to be overwhelmed or are unable to face a task/situation.

answer; training;