Nearly a century ago, journalist Napoleon Hill studied more than 500 self-made millionaires including Andrew Carnegie, Henry Ford and Charles M. Schwab. His interviews and research culminated in the 1937 bestseller, "Think and Grow Rich."
The 80-year-old personal finance classic breaks down what Hill calls the "money-making secret" in 13 steps.
Hill's wealth-building advice remains relevant today. In fact, his book is a favorite of several of today's self-made millionaires, including "Shark Tank" judges Robert Herjavec and Daymond John.