Advertising chief executives should create a culture where people are allowed to fail and "pursue the art of the possible," according to Nadal.
Speaking on a panel at Advertising Week in New York Monday, Nadal said it is vital CEOs in advertising aim high because what works today may not work in three to five years.
He said: "It is about rewarding risk and understanding that when we try new things, two out of three of them won't work. But if you aren't failing, you aren't trying."
Nadal explained there should be a system in place that rewards risk-takers, but also closely measures failures. "Our organization ensures it dissects and analyzes its failures so we do not make the same mistakes twice," he said.
"It is not that we accept failure, but we accept there is risk associated with invention and innovation decisions."
Jim Stengel, former global chief marketing officer of Procter & Gamble and president and CEO of The Jim Stengel Company, said that one of the biggest issues clients face is the fear of failure, which means they are not taking chances. He said: "All of us have a role in changing that."
Stengel said that behaviour and action, rather than words, should be rewarded. But this required clients to redefine success. He added that too many companies, such as the big food companies, define success too narrowly, meaning they get caught by surprise by fast-changing markets.
He said: "Clients get too wrapped up in their own shoelaces. Agencies have the opportunity to raise clients up to an ambitious purpose.
"The best relationships with agencies I have had have been a slap in the face for me."