As a Man Thinketh (1903)
This book changed my life.
Originally by James Allen, I was introduced to this by book by Earl Nightingale, who recited portions of it on his radio program. The power of Allen's words combined with the delivery by Nightingale was life-altering.
You can download "As a Man Thinketh" in various formats from Project Gutenberg.
You can find uploads of Nightingale's audio edit on YouTube.
Sometime I would like to explain when and how this happened, but until then I leave you with this:
A man only begins to be a man when he ceases to whine and revile, and commences to search for the hidden justice which regulates his life. And as he adapts his mind to that regulating factor, he ceases to accuse others as the cause of his condition, and builds himself up in strong and noble thoughts; ceases to kick against circumstances, but begins to use them as aids to his more rapid progress, and as a means of discovering the hidden powers and possibilities within himself.