In our discussion about business success we talk a lot about the importance of grit, failure, and even time management. But in our conversations about leadership one thing doesn't seem to come up often: humility.

I recently keynoted the conference where I spoke about innovation and leadership, which prompted a lot of follow-up conversations with the attendees. But one story, told to me by Gregg Gregory, the founder of Teams Rock and a public speaker, was especially fascinating.

It was a story of humble leadership.

About fifteen years ago Gregory was boarding the Southwest flight flying out of Orlando, Florida. Way in front of him in the boarding line he noticed a man with a giant Mickey Mouse baseball hat on. He didn't think anything about it until he walked onto the plane and saw that the gentleman took a seat all the way in the back of the plane. If you have ever boarded a Southwest flight, you know they don't have an official seating system. People in front of the line get their pick of the best seats on the plane. And normally they choose the ones in front of the plane and normally they choose either a window or an aisle seat. Not only did this gentleman pick the last row of the airplane, but he chose to sit in the middle seat. This struck Gregory as strange. After all, the gentleman was one of the first to board.

As the plane got airborne, Gregory noticed that the man in the Mickey Mouse hat walked all the way up to the front, talked to the flight attendants for a while, then turned around, walked down the aisle and started assisting the flight attendants in serving everyone peanuts and drinks. Eventually he came up to Gregory's seat and said: "Hi. My name is Herb Kelleher. Thank you for flying my airline. Can I get you something to drink?"

"That to me was a definition of leadership," Greg Gregory told me as he wrapped up his story. He never forgot the story. And he carried this lesson in humble leadership with him throughout his career.

No matter how far they rise, great leaders serve others. They lead by example. And they do so humbly.

Kelleher is widely known for his philosophy of servant leadership. He applied it to not only building his company, but to his own daily actions as well. The story above is a proof of that.

In one of his interviews with Investor's Business Daily he said that the Southwest spirit was "the core of our success. That's the most difficult thing for a competitor to imitate. They can buy all the physical things. The things you can't buy are dedication, devotion, loyalty--the feeling you are participating in a crusade." But not every crusade has a leader that puts his people and his customers first. That, in my opinion, is why some of the crusades fail. It isn't the case with Herb Kelleher and Southwest Airlines though. Humble leadership - and putting people first - is what creates and nurtures loyalty, advocacy, and brand love. Herb Kelleher is a leader who inspires it both inside of his company and out.