Final answer:
Stress is the physical and mental arousal to situations perceived as threatening or challenging, encompassing both positive 'eustress' and negative 'distress' types, often associated with the fight-or-flight response.
Step-by-step explanation:
The physical and mental arousal to situations that we perceive as threatening or challenging is called stress. This concept has been explored in various ways, involving physiological responses to demands or threats. Specifically, some types of stress can be positive, such as eustress, which is a low to moderate intensity stress associated with positive feelings and optimal performance. On the other hand, distress is a negative form of stress that can lead to exhaustion and health problems. The reaction we typically associate with stress, such as increased heart rate and sweating, is part of the fight-or-flight response, which is elicited by our sympathetic nervous system when we encounter a perceived threat.