Stress can be defined as a mental or emotional strain on tension resulting from adverse or very demanding circumstances. Stress is usually created when we can't predict our future outcome, feel we can't control a situation, or perceive that there's a threat, a danger, or a perception that something's going to get worse in our lives.

3 DIFFERENT TYPES OF STRESS

1) Physical stress: things like traumas, accidents, injuries, falls, etc.

2) Chemical Stress: flu, bacteria, viruses, blood sugar levels, toxins in food.

3) Emotional stress: family tragedy, second mortgages, single parenting, traffic jams, etc.

When an organism in nature perceives a danger or a threat in its external environment, it activates a primitive nervous system known as the 'fight or flight' response. In this perception of danger, the body instinctively mobilizes significant amounts of energy and resources, tapping into vital reserves to navigate and survive the conditions of the external world. All organisms in nature can tolerate short-term stress. When we switch on that emergency system, there is a rush of energy, adrenaline, and arousal in the body and brain. And those chemicals alter our normal homeostasis. In that state of survival, we switch on that sympathetic nervous system. Our pupils dilate, our salivary juices shut down, and our heart and respiratory rates increase. Blood is sent to the extremities and shut down in the internal organs. 
 

For example, when an animal successfully outruns a predator, the stress response begins to deactivate approximately thirty minutes later, and the body re-establishes balance. Many organisms require rest and repair during this period, as the body needs to come back online for regeneration and energy conservation. However, the scenario changes if the predator remains a constant threat outside the cave, extending the need to sustain a heightened stress response. What if this 'predator' is a co-worker, your boss, or even traffic? What was once highly adaptive becomes maladaptive because you're headed for disease when you turn on the stress response and can't turn it off. 
 

NO ORGANISM IN NATURE CAN LIVE IN EMERGENCY MODE FOR AN EXTENDED PERIOD OF TIME.