I was first turned on to Og Mandino in the early 1990's. His smooth style and kind of "Philip Marlowe" personae intrigued me. He seemed like a swingin' cat!

His book "The Greatest Secret In The World" changed my direction in life; it sort of "prepped the field" for future planting of ideas. As a result my life is much better for it. The book revolves around a set of mantras you recite three times a day for thirty days. Eventually there are assignments to follow and you "graduate" knowing the Greatest Secret in the Universe. I know it!! Not gonna tell though....it's a secret!! 

Really, this book makes you work for the answer and believe me when I tell you, if I were to tacitly reveal such a secret, you'd laugh because it seems so easy. Believe me, it's not. 

Wikipedia: 

http://en.wikipedia.org/wiki/Og_Mandino

http://ogmandino.com