Arnold Donald gets serious when he talks about protecting the environment. After all, as CEO of Carnival Corporation, the world’s largest cruise ship company, his business depends on healthy oceans and clean beaches. “We do not want to not only ‘not do harm’, we actually want to make the environment better, especially marine environment,” Donald says, “because that’s the place we operate the most.”

In fact, Carnival has adopted many environmental practices to reduce emissions, fuel consumption and waste. Arnold says that’s company policy, “Not only because it’s the right thing to do, it’s also a good business thing to do and it gives employees purpose.”

Carnival’s strategy is part of a growing trend called “leading with purpose”. Donald tells Fortune’s Susie Gharib that social responsibility is more than a buzzword at Carnival, it’s a strategic imperative. It is a common theme in a series of CEO interviews Gharib conducted in partnership with The Aspen Institute Business and Society Program (https://www.aspeninstitute.org/programs/business-and-society-program/purpose-of-the-corporation/).

Surprisingly, the philosophical change has turned out positive results as many companies now realize that they can do good and still make money. As Donald says, “In the short-term you might be able to make an extra dollar or two, but in the long-term, doing the right thing, being a great corporate citizen of the world, making a positive difference in the communities you touch, will come back to you ten-fold over on the financial side.”