"Stress is an ignorant state. It believes that everything is an emergency. Nothing is that important. Just lie down.” Natalie Goldberg
The stress reaction is within, not "Out There."
Stress provides strength and energy to either fight or run away from danger and is therefore self-protective 
Stress can be acssociated with feeling angry, afraid, excited, or helpless. It can make it hard to sleep. It can give aches in the head neck jaw and back. It can contribute to habits like smoking, drinking, overeating or drug abuse. A person may not even feel it at all, even though the body suffers from it. 
Stress related diseases evolve when pharmacological changes due to chronic stress are sustained for prolonged periods of time with no relaxation response. Physiological changes follow that damage structures of the brain and promote disease. 
Recent data suggests that acute stress can elicit heart attacks or produce irregular heart rhythms, stimulate platelet function, and increase blood viscosity. In coronary artery diseased patients, acute stress also causes coronary vasoconstriction. The current data links increased activity of the sympathetic nervous system as an intrinsic link in some individuals.  
When stress becomes chronic, an excessive sympathetic nervous system response can contribute to development and exacerbation of …..coronary artery disease, atherosclerosis as well as to endothelial dysfunction.
Stress complicates normal functioning...
Stress exacerbates pain and changes response to medical treatment and drugs,[31,35]
Stress may also effect pain intensity and timing of increased pain episodes in patients with fibromyalgia syndrome and other arthritic diseases.
Stress changes structures in the developing brain ,
Stress impacts wound healing, and fatigue.,,
Stress can disrupt reproductive health