Napoleon Hill published two books on the theme. The first, The Law of Success in 16 Lessons (1928), directly and repeatedly references the Law of Attraction and proposes that it operates by use of radio waves transmitted by the brain. The second, Think and Grow Rich (1937), went on to sell 100 million copies by 2015.[60] Hill insisted on the importance of controlling one's own thoughts in order to achieve success, as well as the energy that thoughts have and their ability to attract other thoughts. He mentions a "secret" to success and promises to indirectly describe it at least once in every chapter. It is never named and he says that discovering it on one's own is far more beneficial. Many people have argued over what it[61] actually is, some claim it's the Law of Attraction. Hill states the "secret" is mentioned no fewer than a hundred times, yet reference to "attract" is used less than 30 times in the text. He further claims that people can obtain what they desire through thought of definite purpose.[62]
Your thoughts and actions create a result. Everything you think, say, and do will have an effect. Every action generates a force of energy that returns to it in kind and that energy continues to flow back and forth. If you don’t have a clear understanding that this is how things are, then the Law of Attraction makes your reality seem like the world is bleak because you don’t understand how you are attracting the very thing you wish to get away from. You just do your best to keep thinking happy thoughts in the hopes that something good will eventually occur.

Is My Desire Manifesting