When companies talk about their values, why do we believe some but not others?

Of course, there’s the ever-present profit motive lurking in the background, but that applies to all companies. The companies that succeed in communicating their values do two things well: They embrace tradeoffs, and they’re not afraid to talk about them. In fact, they understand the power in talking about those tradeoffs openly.

Stories have something to teach us about why. “A story expresses how and why life changes for its characters in terms of the values at stake in their life,” says screenwriting teacher Robert McKee. Stories do this by forcing characters to make choices. “True character is revealed in the choices a human being makes under pressure—the greater the pressure, the deeper the revelation, the truer the choice to the character’s essential nature.”

For example, in this summer’s hit film Baby Driver, the main character must choose between freedom and obligation over and over. Baby takes a stand that costs him—but it also affirms who he is and the possibilities for his life.

In our own life stories, we can see authentic values at work in each difficult choice between two opposing things we may want. Think about a stand you took that cost you an opportunity, a job or a friendship. What was at stake in those choices? Because you were willing to give up something they reveal your true values.

So it makes sense that we see companies that show how they live their values—and what they give up for those values—as authentic, particularly next to companies that merely talk a good game. In stories of the tradeoffs a company makes and the price it’s willing to pay, we recognize the fundamental truth that values aren’t free.

Many companies say they value sustainability, but few have acted upon it like Google. Frustrated that the slow pace of wind and solar development kept it from buying more renewable energy from utilities, Google started fundingwind and solar projects directly with developers. So far, Google has spent $2.5 billion on such projects and is now the largest corporate purchaser of renewable energy in the world. Its drive for 100 percent renewable energy has cost Google plenty of time, money and brainpower. This tells us the company’s value of sustainability is real.

In 2014, in support of CVS’ dedication to human health, the company decided to stop selling tobacco products. The decision cost CVS an estimated $2 billion a year in retail sales. That hurt, but it left no doubt that CVS stands for helping people on their path to better health. The choice also made an impact: Overall tobacco sales in CVS markets declined in the year after CVS’ decision, indicating people had stopped smoking or cut back. And total CVS sales, driven by health-care-related products, actually rose following the decision.

You don’t have to be a CVS or a Google to be rewarded for your efforts. Your company undoubtedly makes business decisions based on your values every day, whether you’re devoting time and resources to developing safer products or investing in better customer service.

Want to make sure you’re getting a return on your values? Tell stories about the ones that cost you something.

Because those are the stories—and values—people will believe.