Jeff Christensen / AP
Tony Robbins.
Robbins, who has coached high-profile people like star investor Paul Tudor Jones and President Bill Clinton, often recommends the book "because it's so small and easy to read and so profound," he told Business Insider.
The short book, published in 1902, is recognized by Inc.com as one of the 10 most motivational books of all-time. It stresses the importance of mastering your mind to turn dreams into realities.
Here are three main takeaways from "As a Man Thinketh":
1. You control your destiny.
"Man is made or unmade by himself," writes Allen. "In the armoury of thought he forges the weapons by which he destroys himself; he also fashions the tools with which he builds himself for heavenly mansions of joy and strength and peace."
While people often believe fate, luck, or other circumstances are the driving forces behind one's success, "As a Man Thinketh" argues otherwise. You cannot choose your circumstances, Allen writes, but choosing your thoughts can influence your circumstances.
Allen writes that doubt and fear have never and will never accomplish anything except failure. Internal thoughts are in your control. Positively changing them can pave the way to success.
2. Become a "master gardener" of your mind.
"Just as a gardener cultivates his ploy, keeping it free from weeds, and growing the flowers and fruits which he requires, so may a man tend the garden of his mind, weeding out all the wrong, useless, and impure thoughts, and cultivating toward perfection the flowers and fruits of right, useful, and pure thoughts," Allen writes.
In the book, Allen compares one's mind to a garden. A garden may either be intelligently maintained or allowed to wildly grow without purposeful boundaries. Similar to the contents of a garden, your thoughts may be properly controlled and groomed. Allen describes this process as becoming the "master gardener" of your soul and the director of your life.
"Good thoughts bear good fruit, bad thoughts bad fruit," he writes.
Thoughts are like seeds - they will continue to grow and multiply. Starting with strong, optimistic thoughts will lead to more of the same, and maintaining those will lead to a better end result.
3. Think big.
"Dream lofty dreams, and as you dream, so shall you become," writes Allen.
Success starts with a dream. That dream, however, has to be more than simply wanting or wishing for something, Allen says. Success must be earned. It's created by having the right thoughts and taking the right actions.
Allen's overarching theme is that any goal is attainable with a well-structured thought process and a strong work ethic. "You will receive that which you earn," he writes. "No more, no less."