Entrepreneur guru and life hacker expert Tim Ferriss asked former NFL player and actor Terry Crews (Expendables 3, Brooklyn Nine-Nine) about books that have influenced his life and one answer came up: The Master Key System by Charles F. Haanel.

“This [book] is the one that clearly showed me how to visualize, contemplate, and focus on what it was I truly wanted,” wrote Terry Crews. The athlete turned actor said the book helped him find “laserlike focus.”

In one passage from the book, Charles F. Haanel wrote, “The finite cannot inform the infinite. You are simply to say what you desire, not how you are to obtain it.” A good chunk of the book focuses on thinking positive and the power of abundance.

For Crews, this meant wanting to be wealthy simply meant thinking, “What would a wealthy person do?” This way, he could make decisions in a pass/fail manner as they came up, knowing he wanted one result.

In another section, the author wrote, “It is only necessary to have a certain number of thoughts on a given subject in order to bring about a complete change in the physical organization of a man.”

Similarly, in the follow-up podcast with Tim Ferriss, Terry Crews told the audience, “Everything that is within your grasp is not meant to be in your hand. Teach yourself to say no. Tell your body what to do.”

Again, the star's focus helped him stay in top shape, while also helping him say “No” to the good in order to pursue the great.

Eventually, the book moves towards the true definition of the “Master Key System.”

The author writes:

“A century ago any man with an aeroplane or even a Gatling gun could have annihilated a whole army equipped with the implements of warfare then in use. So it is at present. Any man with knowledge of the possibilities contained in the Master Key has an inconceivable advantage over the multitude.”

While some sections may sound out of left field, there’s certainly some truth to the book. Terry Crews read it at an early age, but it still remains one of his top personal development books for all of these years.

If this book doesn’t sound like its up your alley, consider starting with Terry Crew’s podcast interview or Tim Ferriss’ book, Tribe of Mentors, for additional solid advice.