I was the nice guy who finished last. It was my first week selling advertisements, and although my clients had a 95% renewal rate I failed to bring in any revenue. Then a client insisted on a refund, and I became the first person in company history to lose money that was already on the books from last year. Now it was time to contact my most difficult client—a hotel operator named Chris. My predecessors had left nearly a decade of notes about how he had demanded 90% discounts and then refused to pay for his ads. When I called him, he said that due to budget cuts, he would need to delay several months before making a decision… unless I could give him a steep reduction in the price.

Ever since then I’ve been studying how to deal with people like Chris. If you want to be a generous giver, you have to watch out for selfish takers. The boss who dumps the grunt work on you and then steals the glory. The colleague who hogs the floor in the meeting. The customer who feels entitled to all of your time. The CEO who fails the A**hole Rating Self-Exam. The new hire who eats your salad from the fridge, and then complains that he didn’t like the dressing.

I spend a lot of my time trying to help leaders build cultures of productive givers. My first tip is to stop hiring takers—their behavior is contagious and they have a toxic effect on teams. Even if they’re competent, their ultimate loyalty is to themselves. A few years ago, I advised a law firm to fire their taker clients. They calculated that a few entitled clients were costing them over $4 million a year. The most dangerous clients were what I call the agreeable takers: the people who are friendly on the outside yet selfish on the inside. It never feels like they’re taking advantage of you at the time. But as I argued in a recent TED talk, at some point it’s best to cut your losses altogether—or at least minimize the damage by limiting your collaboration:

Sadly, many of us are stuck working with selfish takers. Firing Chris wasn’t an option for me: even if he pushed for a deep discount I was depending on his revenue. So I made a plan to change his stripes.

1. Find the Bright Spots

Some people are selfish in all of their relationships. Those people are called sociopaths.

Most takers are not bad people. They’ve just become cynical after getting burned one too many times or being taught that the corporate world is a dog-eat-dog place.

If you pay attention to their actions, you’ll notice moments when they’re less selfish. The trick is to figure out what those bright spots have in common, so you can connect with their motivation to give. Like the programmer I knew who always said no unless you ask him a question about computers—he found them so fascinating that he can’t help sharing his knowledge.

2. Give Reputational Feedback

When Moneyball author Michael Lewis was 14, he went to a tennis camp. At breakfast small boxes of the best cereal were in short supply. On the first two days they all raced for the Fruit Loops—the losers got stuck with diarrhea from bran cereal. On the third day the coach called them together. “You can be a giver or you can be a taker,” he said. “You make that choice every day.” Lewis recalls that they all “squirmed and reddened and glanced at one another, wondering if everyone else realized what an a--hole he'd been.” He told me that from that point forward, no one wanted to be the taker: “Everybody was slow-walking it to the breakfast table.”

This isn’t just for kids. A few years ago at a financial services company, a woman named Kathy got a big promotion. She was leading a new team with a guy named Colin, and four different people warned her not to trust him. In their first meeting she sat down with him and did something courageous: she shared all the reputational feedback. “I don’t know whether it’s true or not,” she said, “But I don’t work well with people who operate that way. If this is who you are, you are not going to like working with me.”

Kathy called out his reputation and gave him a chance to earn a new one. For the next year and a half, he was unusually generous in sharing credit, mentoring junior colleagues, and volunteering for unpopular assignments.

Few people want to look in the mirror and see a taker staring back at them. And even fewer want to be known as a taker. As Cheryl Strayed writes: “we often become our kindest, most ethical selves only by seeing what it feels like to be a selfish jackass first.”

3. Understand their Goals

The nice thing about takers is that if you know their interests, their behavior is fairly predictable. If you can help them see how being selfish jeopardizes those goals, they have a reason to shift their behaviors.

At Facebook there’s a strong culture of collaboration—people are evaluated on their contributions to the team and the company, not just their individual results. COO Sheryl Sandberg once pulled a colleague aside and told him that people didn’t trust him or want to work with him. His previous company had a cutthroat culture, and he had learned to be aggressive in prioritizing his own work over others' needs. “That’s not how you succeed here,” she explained. Not long after he became one of Facebook’s top-rated managers—singled out for his generosity.

The Moment of Truth

When I called my beloved client Chris back, I started by looking for bright spots. I asked why he got into the hotel business, and he said he struggled to travel in his twenties because it was too expensive. That gave me an opportunity to remind him that my company created jobs for students—and I was one of those students. Motivation to give: check.

At that point I leveled with him. “Chris, I see in my records that in the past you’ve threatened to pull your ads just before our deadline if we don’t give you a huge discount. I understand that you want the best value for your money, but I can’t reward that kind of behavior.”

He apologized. Then I appealed to his interests: I had an exclusive ad placement in a key location available for him, but I was contractually obligated to open it up to all advertisers soon. He renewed on the spot. And the next year after the economy crashed, he increased his spending by 10%. Which was good, because I was thinking of handing him over to the one taker on my team.

When all else fails, you can always sic one taker on another.