Leadership is hard. It means making hard decisions and doing hard things. More importantly, it means getting others to do hard things. Depending on what you lead, there are a number of things you can mess up at any time. Sometimes those things will cause you pain. Sometimes they'll cause other people pain. Sometimes they can break your company.

Figuring out how not to mess up seems like an important thing to learn. The problem is, it's not at all realistic. You're going to mess up. If anyone tells you otherwise, they're lying to you. 

That's what I love about a speech Tim Cook, the CEO of Apple, gave earlier this month. Speaking to a crowd of graduates at Gallaudet University, Cook talked about the most important principle of leadership: 

I have one important piece of advice I want to share. So important, that it's the only piece of advice I'm going to share today. And that is this: Whatever you do, lead with your values.

Look, as CEO of the most valuable company on earth, Cook is responsible for a team of 180,000 or so employees who make and sell stuff like the iPhone--the most successful product in the history of, well, ever. Under his leadership, Apple has become one of the largest and most profitable companies ever. I think it's fair to say he has some experience with leadership. When he talks about that experience, it's probably worth your time to listen.

Cook is also an outspoken advocate for the things Apple says it values--things like privacy, the environment, and accessibility. Apple's values, according to Cook, drive everything the company does.

That's why those seven words--whatever you do, lead with your values--might be the most important leadership principle you'll ever hear. You see, leadership and values are inseparable. 

Notice that Cook didn't say to lead from your strength. He didn't say to lead with your heart or with your passion. A lot of people talk about leadership in relation to those things, but Cook takes a less conventional approach to leadership. He says to lead with your values. 

That isn't to say that those other things aren't important. But, leading from your strength without respect for your values can be a dangerous thing. The same is true about passion. 

Your values, on the other hand, are your core guiding principles that inform every decision you make. "By leading with your values," Cook said, "what I mean is that you should make decisions--big and small, each and every day--based on a deep understanding of who you are and what you believe." 

Everything should start with your values. From the people you hire, to the products you design, to the way you sell them, every decision should be informed by who you are and what you believe. 

"As a company, our purpose has always been to create technology that enriches people's lives," Cook continued. "And we believe we can only achieve that goal through a relentless focus on our values. That's why we work hard to make technology that is accessible to everyone. Why we fight to protect the fundamental right to privacy, and why we are constantly innovating to help protect the environment and leave the world better than we found it."

You can disagree with the decisions Apple makes about any number of things. I think it's obvious, however, that the company acts based on what it says it values

That's maybe the most important lesson. As a leader, you'll spend a lot of time making decisions that a lot of people won't agree with. If you lead with your values, you still might get some of the details wrong. You'll still make mistakes, but it's a lot easier to know that you're doing the right thing when you know who you are and what you believe.