On Thursday, I lost an important mentor, albeit one I had never met. Herb Kelleher, the charismatic founder and former CEO of Southwest Airlines, passed away at the age of 87.

Kelleher set the example for what it means to build a great, enduring company that treats people well, and he largely succeeded by defying conventional wisdom. Meeting him was a life goal for me, and I regret that I won't be able to thank him in person for his influence.

Here's the funny thing though: I don't enjoy flying Southwest. It's just not my cup of tea. I fly frequently and appreciate the perks--getting upgrades, boarding first and knowing where I am going to be sitting.

I'm not Southwest's target customer, which is perfectly fine. Great companies don't try to be all things to all people. And that's just one of the great lessons leaders can take from Kelleher's leadership. Here are five more:

1. Treat people well.

Southwest has always been known for treating its employees and its customers well. Kelleher had great relationships with his union, and that trust helped him through a lot of tough negotiations. His airline has not had a strike to this day.

I vividly remember a story from Nuts, a book about Southwest and Kelleher, in which a ticket agent invited a stranded passenger home. And just a few years ago, Southwest made headlines when it went out of its way for a passenger whose son had been in a terrible accident: The airline turned a plane around and worked to reroute Peggy Uhle and her luggage so that she could get to her son, who was in a coma. 

2. Hire for talent.

"We will hire someone with less experience, less education and less expertise, than someone who has more of those things and has a rotten attitude. Because we can train people. We can teach people how to lead. We can teach people how to provide customer service. But we can't change their DNA."

That's why everyone you interact with at the airline is pleasant and often funny, taking the edge off stressful experiences. You can't pull this off the other way around--can you imagine an airline trying to hire experienced flight attendants and then training them to be funny?

3. Be an original.

Southwest, like Kelleher, is one of a kind. Kelleher smoked a pack of cigarettes a day, drank Wild Turkey regularly, ate cheese crackers for breakfast, and apologized to no one for who he was, according to Dallas News.

Southwest showed its own character very early on, when it only had four planes. In 1973, The New York Times detailed how Braniff Airlines swooped in on Southwest's most profitable route and cut prices in half overnight, from $26 to $13. Southwest fought back with a bit of creativity and humor. Knowing the route was popular with business travelers, Southwest offered passengers a choice: Pay Braniff's $13 fare or pay Southwest the full $26 and receive a fifth of Chivas Regal Scotch.

Seventy-five percent of passengers paid the $26 before corporate controllers caught on to the scheme. Southwest went on to become the largest Chivas distributor in Texas, and Braniff eventually bowed out.

4. Stay focused.

Southwest never wavers from its core operating strategies: It only flies one type of plane (Boeing 737), going point to point rather than using the traditional hub strategy, without assigning seats. The airline intentionally decided to be bad at convenience and onboard amenities to focus on being on time and inexpensive. 

The result? Southwest has 45 consecutive years of profitability, according to the company. U.S. government data shows that Southwest carried more domestic passengers than any other airline last year. Trying to be everything to everyone rarely works.

5. Culture matters.

I used to think that corporate culture was BS, largely because I often saw words plastered across the walls of companies that were totally disconnected from how people at the company behaved. Then, years ago, I atteded a conference where a speaker said he'd asked Kelleher the secret to Southwest's success. Kelleher's answer was one word: "Culture."

I did a little research and found that Southwest was consistent with what it says it values and how its people act. That speech led me on a five-year journey to develop a world-class culture at my company.

I still won't be taking a Southwest flight anytime soon, but I've gained a lot from the airline. Every time I see one of those blue, red, and yellow planes take off, I will fondly think of the mentor I never had a chance to meet and the legacy of leadership he left behind.