Few of us can say we have never felt anxiety at some time in our lives. Anxiety seems to be a response to a vague or unrecognized danger. It tends to be out of proportion or unrealistic. Anxiety can come out of nowhere merely by thinking about a situation. Anxiety ranges in severity from person to person and in the same person from episode to episode. Fear is at the root of anxiety. People who have anxiety tend to overestimate the likelihood and the intensity of threat and danger.