I've said it, and many others have too: Having a mentor is a vital part of professional growth. In fact, they're not just the key to your business; they're the key to your personal success. 

Here's my suggestion: Think of your group of mentors as a personal advisory board, packed with a diverse set of perspectives.

For me, for example, having a mentor from every generation is an incredible way to gain insights and learnings. 

I believe personal growth is fundamental to becoming a better leader. That means surrounding yourself with people who are willing to tell you what you're good at, what you're bad at, and when you have blind spots. 

For me, mentors of many decades bring many different lessons -- as the world is constantly changing, people of all ages, genders, ethnicities, and backgrounds bring unique viewpoints to what has changed and then, as you can imagine, remind you of the core values that never change. 

Take one of my mentors, for example, who's in his 70s. He's taught me the value of picking up the phone. 

This is especially important anytime you're dealing with a tough or personal issue, any kind of impactful meeting, or any major decision that needs to be made. It's always easier to send a text or an email, but that needs to be a conversation. 

How did I learn this valuable lesson? One day, he just dialed my number. I was 22 years old and had just introduced him at a Bloomberg event. The next morning, he picked up the phone and called me to thank me. That left such a lasting impression on me. First, I was so confused -- I forgot that you can just call people, and that you don't need to schedule a meeting to do it. Second, the fact that he took the time to take two or three minutes to call me made me feel so important and made me realize the sheer value of calling people and letting them hear your voice. 

Another time, I was meeting him for breakfast. It was at 8 a.m. at my office, so I showed up at 7:45. There he was, standing outside the building 25 minutes early, holding his paper and his coffee and locked out because I wasn't there to let him up. 

We've lost the value of time as a generation (though I still think 15 minutes in advance is OK). But here's the thing: When you have personal meetings, never, ever, ever be late.

I turn to another mentor, Ann Kaplan, for advice on everything from friendships to marriage to ensuring long-term success. Her business value system is impeccable, and is one of the best things that I received from someone with her great experience.

And then there are my peers. One of my best friends in life, Lucy Deland, the COO of Paperless Post, is also one of my best mentors. I go to her not just for our friend dynamic but also for business advice. She's my peer, and is my age, but I go to her with my work challenges because she always provides me with a perspective that I hadn't thought through. 

Some of my best friends from my Henry Crown fellowship -- from the CEO of Sprint, Marcelo Claure, to the COO of the New York Times Company, Meredith Kopit Levien -- are my first phone calls if I have a challenging dynamic to handle.

I have mentors of both sexes, married, unmarried, with kids and without. Here's the twist: Have a mentor who's in their teens. Ask them honestly for their opinions and for their help -- they're so much better at technology than the rest of us. I am constantly making sure that I have one or two incredibly savvy young people to learn from (often, I'm helping them get internships, too, so the relationships aren't one-sided). 

Sourcing advice and inspiration from people from all of those different walks to make up my personal advisory board helps me lead my business -- and my life. And, as always, personal growth is a work in progress!

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