Running a team is hard because it ultimately boils down to people, and all of us are multifaceted and complex beings. Just like how there is no one way to go about being a person, there is no one way to go about managing a group of people.

And yet, working together in teams is how the world moves forward. We can create things far grander and more ambitious than anything we could have done alone. This is how battles are won, how innovation moves forward, how organizations succeed. This is how any remarkable achievement happens.

I believe this as deeply as I believe anything: Great managers are made, not born. It doesn’t matter who you are. If you care enough to be reading this, then you care enough to be a great manager.

If the job is defined as getting better outcomes from a group of people working together, then a great manager’s team will consistently achieve great outcomes.

As a manager, you are judged on your team’s outcomes, so your job is to do whatever most helps them succeed. If your team is lacking key skills, then you need to spend your time training or hiring. If someone is creating problems for others, then you need to get him to stop. If people don’t know what they should be doing, then you need to construct a plan. A lot of this work is unglamorous. But because it’s important, it must be done, and if nobody else does it, then it falls to you.

This is why adaptability is a key trait of great managers. As your team changes—whether it’s goals shifting, people joining or leaving, or processes evolving—what you do every day will also change.

Leadership is a quality rather than a job. We are all leaders and followers at different points in our lives. Many aspects of this book should be useful to those looking to grow as leaders as well as managers, and great managers should cultivate leadership not just in themselves but also within their teams.

This is an important distinction because while the role of a manager can be given to someone (or taken away), leadership is not something that can be bestowed. It must be earned. People must want to follow you.

Remember our definition of management? A manager’s job is to get better outcomes from a group of people working together through influencing purpose, people, and process.

With a small team, maintaining a shared sense of purpose is straightforward. You don’t get many crossed wires when your team can still fit around one table. That leaves people and process to focus on. Of those two, people are by far the most important.