With this revelation Earl Nightingale wrote and recorded a message called The Strangest Secret, and with it pioneered the personal development industry. Earl Nightingale's radio show, Our Changing World, was the most highly syndicated radio program of it's time, spanning more than 40 years. Earl Nightingale was heard daily, across the United States, Canada, Mexico, Australia, Bahamas, Guam, New Zealand, Puerto Rico, South Africa, the Armed Forces Radio, and thirty countries overseas, earning him a place in the hallowed Radio Hall of Fame. [learn more about Earl Nightingale]