It was early 2004, and Scott O’Neil, the National Basketball Association’s newest executive, was pacing around his new office, 14 floors above St. Patrick’s Cathedral in midtown Manhattan.

His promotion to Senior Vice President of Team Marketing and Business Operations gave him direct supervision of dozens of league office employees and oversight of every NBA team’s ticket office. But his assignment was big: increase attendance in a league where season ticket sales were flat and the new crop of superstars had yet to emerge.

Jump ahead and this story does have a happy ending. For each of four consecutive seasons, O’Neil’s team was instrumental in NBA franchises, setting the all-time record for regular and postseason attendance. More than 100 million fans visited games during the period, and team sponsorship revenue showed double digit increases annually.

But during his first days on the job, such success seemed like a farfetched dream. "Things were okay. We had huge brands, accomplished executives, and good relationships. But we hadn’t come together as a great team," he said.

O’Neil decided to call his team together to talk through the opportunities in front of them. Eventually, a small set of team rules--or values--began to emerge from their discussion.

"This wasn’t about the boss coming in and saying, 'These are the rules.' That never works," said O’Neil. Instead, it was about building something together. "We debated and discussed until we got buy-in from everyone."

How many rules did the team agree to? A simple set of three.

"There is magic in three," explained O’Neil. "Our brains function in a way that three things are easy to remember and we can draw on them in our daily lives. One value never seems to encompass everything, and more than three is too many to drive and stick."

The team’s commitments were:

Wow. The marketing team would hold itself, and their partners throughout the league, to a world-class standard of performance.

No Surprises. All team members would engage in open communication with one another, establishing clarity of expectations, freely debating issues, disagreeing if they had a good reason to, and sharing ideas.

Cheer. The team would root for each other, which included appreciating great work, providing support, and avoiding disparagement.

After adopting this Rule of Three, O’Neil’s team began with a simple question: "How are we going to impress each other?" That led to a debate on regular and postseason attendance numbers and team sponsorship revenue, which prompted a unique commitment.

"We decided that when we woke up in the morning and looked at ourselves in the mirror we had a decision to make: 'Am I going to be great today?'" said O’Neil. "When we walked into a meeting we made a decision, 'Am I going to be great in this meeting? Have I prepared properly? Do I have the right attitude? Have I done the research? Am I willing to share and receive?'"

Because the team committed to be great (Wow), because they shared everything (No Surprises), and because they learned to encourage each other (Cheer), O’Neil created a breakthrough team at the NBA league office, with practices that spread around the rest of the league. And it led to even bigger things for this great leader. O’Neil went on to spend five years as president of Madison Square Garden Sports, and was just appointed this summer as CEO of the Philadelphia 76ers.

O’Neil’s story is remarkable but certainly not unique. All around the world, we've found leaders introducing a similar set of rules to their teams and getting buy-in among their colleagues--moving them toward world-class results, openness, and a positive culture.

Keep it simple. Develop your team’s own Rule of Three and see if people will rally to your cause.