Warren Buffett hasn't really allowed us inside his personal life. That is, until Alice Schroeder got unprecedented access to explore with him his opinions and philosophy of life.

That exploration resulted in the book that Buffett himself would never write: The Snowball: Warren Buffett and the Business of Life. And we can all thank her for it because it's filled with rare gems.

Buffett on picking the right place to work.

On the topic of career advancement, consider what Buffett has to say:

People ask me where they should go to work, and I always tell them to go to work for whom they admire the most. It's crazy to take little in-between jobs just because they look good on your resume. That's like saving sex for old age. Do what you love and work for whom you admire the most, and you've given yourself the best chance in life you can.

So whom do you admire the most as a potential future boss? Being that we spend more awake time at work than with our own families, this is an important question.

To differentiate truly admirable bosses from mediocre ones, let's look at some clear examples of what the best leaders do to be called "admirable."

1. Admirable leaders are relationship-driven.

It's not surprising that managers who have the trust of their employees also develop strong and healthy relationships with them. Gallup research affirms this as a critical driver for success. It states that "the personal relationship [employees] have with their supervisor is the most meaningful relationship they have with their organization."

On the flip side, the effects of a bad relationship with the boss are so serious, it's a detriment to the health of workers. From Gallup's "State of the American Manager" report:

Having a bad manager is often a one-two punch: Employees feel miserable while at work, and that misery follows them home, compounding their stress and putting their well-being in peril.

Now imagine that same employee coming to work the next day, feeling completely demoralized and demotivated. What will that do to their performance and team morale?

Remember, admirable leaders are labeled as such because they truly care about individual contributors on a human level. They are sincerely interested in getting to know them -- their interests, concerns, dreams, strengths, gifts, and goals.

2. Admirable leaders create safe space for risks to be taken.

In an effort to discover the secrets of collaborative teams, Google's own researchers set out to answer one overarching question: What makes a team effective at Google?

The study, code named Project Aristotle, arrived at some interesting conclusions. Researchers discovered that what really mattered had less to do with the people on the team, and more to do with how team members worked together.

On top of the list was the need for teams to experience "psychological safety" -- a shared belief held by members of a team that the team is safe for interpersonal risk taking, that "no one on the team will embarrass or punish anyone else for admitting a mistake, asking a question, or offering a new idea," wrote the researchers.

When bosses set the foundation for teams to experience higher psychological safety, employees were less likely to leave Google and more likely to harness the power of diverse ideas from their teammates. And, if you're wondering, this level of creative freedom and risk-taking without fear or reprimand brought in more revenues for the company.

3. Admirable leaders display uncommon humility.

It's been found that the most admirable leaders demonstrate humility (like Level 5 Leaders documented in Jim Collins's Good to Great) and turn away from selfish interests. While not exactly a "power" word, research continues to define and validate humility's leadership effect on others.

In Good to Great, Collins determined from his own extensive research that these respected leaders direct their ego away from themselves to the larger goal of leading their company to greatness.

In essence, humble leaders achieve greatness without arrogance. They shift from ego to humility, which can drastically alter the outcome to their advantage.

4. Admirable leaders, in the end, will make those around them better.

To elevate your impact as a leader, remember this: Leadership is about service to others. To assess where you are against the high measure of a servant-leader, there's one very powerful question you need to ask right now:

What am I doing every day to improve the life of an employee?

That's what it comes down to. When you can exercise the leadership traits that result in trust and commitment and loyalty in your employees, when you can remove obstacles in their path and set them up for success, when you can give their work meaning and purpose, you will be the most admirable leader in the eyes of others.