“One of these tactics is for the frightened person to realise that in most cases, the fear created by the expectation of a threatening experience is much greater that the real experience itself, if it actually occurs. This is because most of what man is afraid of is not really as harmful as he expects. This is confirmed by the saying that ‘most of what you fear will not harm you’ and the other saying, ‘most of the terror comes from the anticipation of the terror.’”
Abu Zayd al-Balkhi - Sustenance of the Soul - The Cognitive Behavior Therapy of a Ninth Century Physician - Malik Badri