Napoleon Hill: Self-discipline
Self-discipline begins with the mastery of your thoughts. If you don't control what you think, you can't control what you do. Simply, self-discipline enables you to think first and act afterward.
Napoleon Hill (Pound, county of Wise, VA, October 26, 1883 - South Carolina, November 8, 1970) was an American author in the area of the new thought movement who was one of the earliest producers of the modern genre of personal-success literature. He is widely considered to be one of the great writers on success. His most famous work, Think and Grow Rich (1937), is one of the best-selling books of all time (at the time of Hill's death in 1970, Think and Grow Rich had sold 20 million copies). Hill's works examined the power of personal beliefs, and the role they play in personal success. He became an advisor to President Franklin D. Roosevelt from 1933 to 1936.