In the words of Muhammad Ali, "Impossible is just a big word thrown around by small men who find it easier to live in the world they've been given than to explore the power they have to change it. Impossible is not a fact. It's an opinion. Impossible is not a declaration. It's a dare. Impossible is potential. Impossible is temporary. Impossible is nothing."

At a time when so many leaders are more consumed with short term wins than shaping the future, Musk works feverishly towards his long-term goals. Many of which seem impossible or can't be done. He is realizing some of the most aspirational goals in human history, and building his legacy right before our very eyes. It's as if nothing can knock him out of the ring, derail his ambitions or make him throw in the towel.

Here's what Elon Musk can teach you about living life with grit:

You Only Fail When You Quit

All our life, we encounter people and situations that cast doubt upon us and write us off. They challenge our ability to realize a vision. They question our intellect. They say we don't have what it takes. These words can breed insecurity, and even make you quit if you don't believe in yourself.

"I had so many people try to talk me out of starting a rocket company, it was crazy," Musk said.

He's been denied, rejected, ridiculed, and to some, thought to be downright crazy. Forced out of PayPal. Personally went broke in 2010. Accused of not getting better at building cars. Watched the Falcon 9 blow up. It seems like quite the laundry list of failures. But the truth is he's never failed, because you only fail when you quit. Like Musk advises, "When something is important enough, you do it even if the odds are not in your favor."

Even When You Win, Keep Fighting

In 1995 after hearing a terrible sales pitch from a Yellow Pages rep, Musk and his brother Kimbal realized that the company had no real sense of the power of the internet. He turned their weakness into an opportunity and created Zip2. Zip2 provided an internet presence for businesses by linking their services with searchers, and provided directions to their retail base.

Musk sold Zip2 in 1999 and personally netted $22 million. Right then and there, he could have retired, but he didn't. He was onto even bigger and better things. He started another business, and another and another. He kept going and didn't just settle for winning big.

It's Not About the Money, It's About the Mission

Musk allegedly made $180 million from the sale of PayPal to eBay. Staggering amounts of money to live on if that's the only thing that drives you.

For Musk, it's clear that it's not about the money, it's about the mission. He invested in Tesla. He launched SpaceX. He's trying to put people on Mars. He wants to build a tunnel underground to improve traffic. He isn't just working for the paycheck. Musk has a greater purpose.

When you have a purpose that's greater than how many dollar signs are behind your name, it gives you the internal fortitude to press on -- despite what obstacles you might face.