Ever since I turned 30 and went through my quarter-life crisis, I've been fascinated with the definitions of success and fulfillment. In my quest, I've studied and spoken with leaders from Warren Buffett (fun fact: I once served as his bodyguard...a story for another time) to millionaire entrepreneurs that most have never heard of.

A little over a year ago, when I was just starting my book-writing process, an entrepreneur friend of mine told me the secret to his writing success, and at first I couldn't possibly fathom that what he was saying was true.

His solution: be vulnerable.

Before you assume this is just another article about how being vulnerable is the secret cure-all to business, appropriate vulnerability isn't about simply sharing the deep, dark secrets of your life.

Rather, there's a secret power to vulnerability that the best business minds of our time frequently use to endear a massive and loyal following, which is a huge key to their financial success.

The biggest business leaders in the world are never afraid to share who they really are.

Consider the Oracle of Omaha. In his first authorized biography, author Alice Schroeder spent more than 2,000 hours with Buffett. Over those 2,000 hours, Schroeder saw him "weep and suffer and be in real emotional pain," which she described as being the most surprising thing she saw in their time together.

Perhaps even more surprising? That Buffett "is sensitive to criticism from other people [and about] how he's being perceived," a vulnerability that Buffett apparently made no attempt to hide from her as he exposed his true self.

Then consider Elon Musk, who once shockingly replied to a tweet asking if he were bipolar by saying "Yeah...Maybe not medically tho. Dunno. Bad feelings correlate to bad events, so maybe real problem is getting carried away in what I sign up for."

Musk could have simply not responded, choosing to maintain his public image of super-smarts, foresight and control. Instead, he unapologetically opened his mind to let us all see a regular man debating the age-old balance of ambition and happiness.

Then there's Tim Ferriss, who not only admits that he suffers from depression, but recorded a full six-minute video about it, when he could have way more easily chosen to do and say nothing at all.

You don't have to be a business titan to be vulnerable.

I was reminded of all of these stories a few weeks ago when I got an email from one of the top podcasters in the world, John Lee Dumas of Entrepreneur on Fire. Just before Christmas, he had received a vicious hate email that blasted everything from his style and physical appearance to the validity of his download numbers.

But instead of dealing with it on his own, Dumas exposed the content of that email -- almost every word of it -- on his Facebook and email list, which perfectly capitalized on the power of vulnerability that Buffett, Musk and Ferriss have embraced.

Here are the lessons we must learn about building an inspirational empire from these brave examples of super-vulnerability:

1. When you're transparently vulnerable, people can't help but trust you more.

Leaders like Buffett have a lot to lose by being transparent about their feelings. And yet, instead of hiding the pain, they all choose to be transparent about their own humanity.

Smart leaders know that their stakeholders, investors, customers and communities will appreciate their transparency, and in turn they create a trust that simply can't be forged behind a media-trained facade.  

With so much disregard for the truth these days, being vulnerable is an easy way to give your constituents the message that you are for real.

2. Being open, honest and vulnerable about who you really are will inspire a lot of people (and it's better for business).

As scary as it might be for leaders to share their vulnerabilities with the world, the truth is that openly sharing is a surefire way to bring any tribe together and endear an audience to you.

"I think the reason the [email] impacted people is that they typically see me happy and energized," Dumas said of the reaction he got to sharing his low moment with his tribe. When they saw him sharing the not-so-great parts of his life, it created a real bond between him and his audience.

"That's the key to building an audience that really knows you as an individual," he realized, which is a fantastic insight for any of us who use our personalities as personal brands.

3. In today's world of fake news, you can always capitalize on the power of honesty.

The crazy thing is that, as hard as it might be for us to follow this mantra, being vulnerable isn't new. The most powerful business minds in the world -- including Buffett, Musk and Ferriss -- all know that actively choosing to be open and honest brings real, tangible and inspirational power.

We all have a huge lesson to learn from these brave choices, which is that choosing to be honest about who we really are will always be the best way to humanize our experiences and inspire others.

If you think about it, their choices to share couldn't fail; after all, when people are open and vulnerable with us, we don't typically stomp on their emotions and hit them while they're down. Instead, we appreciate their honesty, feel empathetic toward their plight and end up liking them even more.

The next time you're faced with hiding your pain, think about these leaders and consider being open about your reality. The more stories we share with each other, the more we can inspire others and build a supportive community -- a community which will directly help you achieve your biggest goals.