It's very real..we evolved with it hardwired into us..I experienced it the day I was told I had throat cancer..and when I was jumped by 2 men in a parking lot..

Without the emotion of fear, we might not have survived. Fear is nature's response to that which threatens life and limb. The sudden release of adrenalin may have been all that was needed to keep one alive so that they could reproduce. Those who were too stupid to be afraid either became heroes or supper. But fear cannot be allowed to dominate the psyche—those who live in a constant state of fear are not only emotionally, but physically unhealthy. And fear is inextricably linked to anger, that other base emotion.