How can stress actually be a good thing?

Stress is a natural part of us humans and shouldn’t be treated as something bad, in facts stress can make you work harder than ever and stress is also a vital warning system, producing the fight-or-flight response. When the brain perceives some kind of stress, it starts flooding the body with chemicals like epinephrine, norepinephrine and cortisol.

Is that a negative 22 or a positive?