Cornell University Mental Health Resource

What is stress?
Stress is an automatic response to demands, pressures, and competing priorities. It's also a normal part of life. Not all stress is bad. Some stress can motivate people, helping them achieve goals. But too much stress, or stress carried too long, can activate a person’s “fight or flight” response. If left unchecked, this can decrease the ability to function. People’s responses to stress vary.
The Stress Continuum explained
A low to moderate level of stress can be productive. Students in the “green zone” experience low to moderate levels of stress as motivating and can help them focus on what they have to get done. To stay in this green, healthy tension zone, individuals can manage their stress with activities that replenish the physical, mental, and emotional energy lost to stress.
Peak performance is when someone is at their very best. This means feeling energized, grounded, and focused on the important tasks at hand like taking an exam, giving a presentation, or having an important conversation with someone. Peak performance is time limited, and can be achieved when you have a manageable amount of stress that acts as a motivator. Once the task is completed, it is important to take a break and do something less intense or something that helps to replenish your energy and reduce the level of stress bringing you back into the green, healthy tension zone.
The yellow zone of the stress continuum represents the point of diminishing returns. This is when someone has been carrying stress for too long, or attempting to stay at peak performance and continuing pushing forward without taking purposeful, restorative breaks. A person in this yellow zone may think they are working efficiently but actually their performance level is declining and they feel fatigued, out of balance, or they may even start to feel overwhelmed by what they need to get done.
Too much stress, or stress carried for too long, can push someone into the orange or red zone. This end of the stress continuum is where someone is experiencing anxiety, exhaustion, and burnout because their level of stress is too high.