How Situational Stress Arises. A very good explanation by a western Buddhist Monk Vimalarisi.
Attention Causes Stress. Dr. Les Femhi amazing research - Open Focus Brain & Dissolving Pain. A must read!
Since birth you have been conditioned to force your brain into fight or flight imagined crisis mode during the daily waking state by only experiencing the world via visual/auditory senses which is only two out of six senses. This way of paying attention creates and stores stress, and we are not even aware of this.
Dr. Femhi call this way of experiencing the world as "Narrow Objective Focus"