Elon Musk is one of the most purposeful leaders on the planet. He understands that success doesn't happen overnight. At times, you might privately think you can't go on. You must persist. As the best leaders know, what you must commit to first is focus, energy, and discipline to finding your "why" -- your reason for being. In The Journal of Positive Psychology, researchers showed that leaders who imagined their "best possible self" for one minute and then immediately wrote down their thoughts generated a significant increase in positive outlook. The researchers concluded that knowing your purpose could indeed increase expectations for a positive future.

Here are three rules for success.

1. Willpower

Do you have willpower? This means the determination to not give up. When you find something you're truly passionate about, it will prioritize itself. You've heard the advice before: Do what you love. To make your own mark, you must first match your "why" with action, persistence, and effort, and then a chemical reaction will start that will enable rapid growth beyond anything you thought possible. Willpower is a decision. Now you must commit to it, and show daily courage to turn talk into action. Just look at how Elon Musk is using his "why" to disrupt every sector with SpaceX, Tesla, Solar City, and Powerwall.

2. Way power

Do you have way power? This means knowing where you are going. It's about clarity and sharpness of direction. In July 2013, 28-year-old Karen X. Cheng became a YouTube sensation when she released a video diary of how she learned to dance like a pro in just 365 days. Each and every day, she would practice with huge levels of discipline. Nothing stood in her way. Flu, tiredness, and occasional days when she simply did not want to dance were pushed aside in the pursuit of her goal. This social experiment went viral worldwide, gaining more than four million views within days. The lesson here: Invest time in yourself to understand who you are and what your "why" is, and then get started.

3. Best personal self

How often do you get to be the best version of you? Your "best possible self" (BPS) is the overlap between purpose (your reason for being), talent (your skills and strengths), and effort (your determination). It's the sweet spot, or as TED sensation Sir Kenneth Robinson describes it, "your element." To unlock your BPS, you must embark on a journey of self-discovery, learning, and renewal. Ancient Greek thinking summed it up best in two words, inscribed on the forecourt of the temple of Apollo at Delphi: gnothi seauton -- "Know thyself."

Summary

Human beings are meaning makers. The most ancient part of our brain, the reptilian brain at the back of our head, finds meaning through purpose. Wharton professor and best-selling author Adam Grant explains why purpose matters more than ever. "If you look at the data, what most of us are looking for is a sense of meaning and purpose," he says. "And when you look at, in turn, what makes work meaningful, what enables people to feel that their daily lives in organizations are significant -- more than anything else it's the belief that 'My work makes a difference.' That 'What I do has some kind of benefit or lasting value to other people.' And I think this is something a lot of leaders overlook."

The best leaders use purpose as a business and life enhancer. Are you ready to unlock yours?