What is Stress?

Stress has been blamed for most modern illness.
From high blood pressure to a weakness of the immune system with frequent colds up to cancer or diabetes consequences of stressful living seem the be at the orign of disease.

But what is stress? Isn't stress only stressfull if I think it is? Is stress dependent on what I tell myself?

There are certain stressors which affect most people:
Physical stressors such as too much noise,  activity, pollution, confusion.
Emotional stressors such as cheating of a partner, death of a loved one, accident of a child, fear of failure, etc.

On the other hand people found it stressfull when Columbus sailed over the horizon into “hell.” A misbelief, which made people faint on the beach. And if I tell myself that a partner's behavior affects only the partner I can be free from the stress of his/her unexpected behavior.

Or: once I realize that my anger only hurts me and I stop replaying thoughts of resentment in my head and choose forgiving to get free from the past, I avoid many consequences of chronic anger, such as high blood pressure or stomach ulcers.
 
So do we only have to change our minds about our expectations and stress to be free from its negative consequences?

What do you think?

Re: What is Stress?

“Stress is nothing more than a socially acceptable form of mental illness, and can, to a large extent, be eliminated. Stress is not something “that happens to us,” but rather something that develops from within our own thinking. From the inside out, we decide what is and what is not going to be stressful.”
Richard Carlson, “You Can Be Happy No Matter What,” page 94