Over the past two years, I’ve recorded 178 conversations (for my podcast The Learning Leader Show) with some of the greatest leadership minds in the world: CEO’s, Entrepreneurs, Professional Athletes… I look for those who have done two things: 1) Sustained excellence over an extended period of time. 2) Have an understanding WHY they’ve performed at such a high level.

I recently sat down, reviewed transcripts, listened to many episodes, and pulled out the best answers to the one question that I consistently ask: “What are common characteristics of those who have sustained excellence over an extended period of time?” Here are the 18 best answers:

78. Kat Cole, Group President of Focus Brands – I think most about the productive achievers, who not only have traditional accomplishments but have also brought others along with them and made a difference.

Envision a scale: It’s a balance of two buckets ..of characteristics. The first bucket is courage and confidence. Productive achievers have a really well-built muscle around courage and confidence. They take risks and believe in their point of view. On the other side of that scale is another bucket: curiosity and humility. Leaders that have this bucket convey to others that they don’t know everything and, therefore, need the people around them. If you get one of those buckets too heavily weighted and the person gets out of balance, it’s very difficult to have sustained success. If you are too courageous and confident, then you’re a bull in a china shop. And if you’re too curious and humble, then you’re just a student.

127. Adam Grant, Bestselling Author, Wharton’s Top Rated Professor, TED Speaker – The most consistent attribute of wildly successful people is that they are dedicated learners. No matter how much excellence they achieve, they are always raising the bar. The more they accomplish, the more they expect of themselves, and they always have something new that they’re excited to learn. If that’s your goal, you’re always getting better and always gaining new insights. Curiosity is the starting point for all originality. When people come up with ideas that are not only different, but better, they began from looking at something and saying, “Why is it that way? Does it have to be that way? Is there another way to do it?”

107. Simon Sinek, Author and TED Speaker – Most people say vision and charisma, but I don’t think that’s true. One thing that I’ve found consistent among great leaders is courage. It takes tremendous courage to stick to your values when there are pressures from the market or superiors who want an expedient route. It takes tremendous courage to stick to your vision. It may take short-term personal sacrifice.

117. Tim Urban, Co-Founder & Writer of ‘Wait, But Why’, TED Speaker – If you want to boil it down, it comes down to having a voice that makes a splash. It’s about the level of impact one makes. Picture a white canvas. Most people paint in white, which means they’re contributing but they’re not changing the image. It’s white on white. But when someone challenges conventional wisdom, they change the entire image. The normal thing to say in the ’70s was that a personal computer would never be in someone’s home. Steve Jobs comes out with the Macintosh. He’s now painting in blue. Then, he keeps reinventing himself. He created a new way to listen to music, then a new phone, then a tablet. Now he’s painting in red. He kept painting in new colors.

86. Seth Godin, Best Selling Author, Entrepreneur, Hall of Fame Marketer- The only thing I’ve seen that these leaders have in common is that they’ve made a choice. And that choice is to make a difference. It’s easy to not make that choice. And if you do not make that choice, it is easy to believe that leadership belongs to other people, that the fickle finger of fate points to someone else by means of luck or good fortune. But it my experience, it is a choice.

114. Cal Newport, Professor, Best Selling Author – The leader respects how hard everything is that’s worth doing. If I was ever asked to give a commencement address, the title would be “Everything is Harder Than You Think.” Those who recognize that real, impactful work does not simply unfold with a clever combination of life hacks and prepare themselves for that battle, they’re the ones that produce at a really high level as opposed to those that have a quick flash in the pan.

115. Amy Porterfield: Social Media Strategy Consultant – The first word that comes to mind is consistency. I have really studied my mentors to understand how they keep moving forward. What I’ve noticed, in all of them, is that they are consistently creating content and they are consistently showing up. They are out there, doing what they’ve promised, over and over again.

42. Rob DeMartini, CEO of New Balance – My list of common characteristics among successful people has four things: The first, one that I always see, is that they are curious. They want to understand how things are working, how things happen, and if things could have happened differently. If you’re curious, it opens up questions and leads you towards learning that otherwise you wouldn’t have. The other three: energy, optimism, and a high sense of personal awareness. That last one is perhaps most important. Do you have a sense of how you’re being perceived, and do you understand how they are receiving your message?

105. David Burkus, Bestselling Author, Professor, TED Speaker – They have a consistent dissatisfaction. They have to balance the tension between stepping back and saying, “I did that and I am proud,” and looking at their work and seeing where they could have done better. Really, it’s a balance between gratefulness and dissatisfaction that keeps people striving for sustained excellence.

82. Dan Pink, Bestselling Author, TED Speaker – Curiosity. They follow their noses. They become interested in things even when they know a lot of things, in fact especially if they know a lot of stuff. The consequence of knowing a lot is in turn knowing how little you know. Also, and this is not uniform, but in many, many cases there is an element of generosity to these folks. Many of them are willing to help others, they aren’t people who pull up the ladder once they reach the top. And the third thing is that they are extraordinarily hard-working and conscientious. The old-fashioned virtues of persistence and grit and conscientiousness are hallmarks.

74. Tim Kight, CEO of Focus 3 – I have three decades of observation and research on that question, but here are the core things: People who consistently perform at the highest levels are intentional, purposeful and consistently building a skill. These people act and think with more intention, purpose and skill than others.

77. Adam Braun, Entrepreneur, Author, Founder Pencils of Promise – Three things stand out to me. The first is, they are tremendously and intrinsically motivated. They aren’t motivated by the extrinsic things. They may not care about the big house or the nicer car or more money. The successful people are simply motivated to be a better person tomorrow than they are today. Second, they display a tremendous amount of integrity. Integrity is the currency that buys trust. And the third is that they surround themselves with people that don’t play on their level, but play on the level above them. They’re always trying to play on the big kids’ court. They’re the eight-year-old trying to play with the 12-year-olds.

48. Cameron Herold, Best Selling Author, Entrepreneur, “CEO Whisperer” – One is sense of vulnerability. They’ve checked their ego at the door, and they’re not trying to be anybody except who they actually are. They’re authentically themselves. Another one is that they realize they are not the smartest person in the room. They’re trying to surround themselves with brilliant people. And they have a sense of curiosity. They aren’t there to talk about themselves. They’re intrigued with other people and with learning in the world.

122. Sarah Robb O’Hagan, Former President of Equinox, Gatorade, Nike – One of the biggest single things is curiosity, without a doubt, and that goes hand in hand with humility. They don’t ever feel like they’ve reached the top of the mountain. They don’t ever feel like they have all the answers. They’re always looking for more. And, even though many of them are often the best in the world at what they do, it’s that extraordinary humility that makes them feel like there’s more to do.

98. Alison Levine, Mountaineer, Bestselling Author, Key Note Speaker – A common characteristic is resilience more than anything else. You have to have that strong sense of resilience. You don’t have to be the best or strongest climber to get to the top of the mountain. You just have to be absolutely resilient about putting one foot in front of the other.

68. Joey Coleman, Inspirational Speaker, Entrepreneur – If I had to sum it up, I’d say it’s three things. First, they have a growth and learning mindset. They are constantly searching for knowledge, whether it be within their industry or beyond. They’re constantly consuming information and experiences. Secondly, these leaders have a common thread of gratitude. They understand how lucky and blessed they are. They appreciate the blessing and gifts in their life. Finally, the very best leaders are gentle with themselves. All too often, we can let our drive and desire to succeed become an all-consuming force inside of us, and it’s paired with a belief that we need to push even harder. The very best leaders can pause and occasionally stop that drive.

108. Steven Kotler, Author and Journalist – First and foremost, these people are ferocious about forward progress. There’s nothing mild about how they attack life. It’s full steam ahead. Everybody I’ve ever met who is super successful, either consciously or unconsciously, has created a life that maximizes the amount of time they can spend in the optimal state of mind for performance.

43. Philip McKernan, Inspirational Speaker – The eyes. It’s in the eyes. You can look into someone’s eyes and know if they’re aligned with the work they do and if they have peace of mind. If someone has peace of mind, it emanates out of their soul and, therefore, out of their eyes. I’ve used the eyes as a tool to call “bullsh%t,” for lack of a better term. If they’re not aligned, then their work is not expression of their soul, and thus not who they are but rather what they do.

Ryan Hawk is the host of The Learning Leader Show. A podcast born out of an innate curiosity to learn from the greatest leadership minds in the world. Forbes called it “The most dynamic leadership podcast out there.” Inc Magazine said it’s “One of the 5 podcasts to help you lead smarter.”