But during the dark days of the Great Recession, Kullman was a motivator above all else.

Speaking with Fortune executive editor Stephanie Mehta at Fortune’s Most Powerful Women Summit in Laguna Niguel, Kullman recalled the challenges she faced rallying her troops during the economic downturn. “I started my job right at the beginning of the financial crisis,” she says. “And people didn’t want to run with you. They wanted you to tell them what to do.” That, she said, was “exhausting,” but she said she just had to continue repeating the same message. “You just have to continue that drumbeat,” Kullman said, responding to Mehta’s asking her what the “least fun” part of her job was.

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As for the more fun part of her job, Kullman mentioned the challenge in proving to investors that there is a return on the $2 billion a year DuPont (DD) spends on research and development. “We do spend $2 billion a year on R&D, and that’s a lot of money,” she said. “Investors say, how do you know if you’re getting a return from that investment?’” She said she gives them “mileposts,” proof in the form of margin expansion, products that didn’t exist four years ago, and other metrics. “I spend a lot of time understanding we’re getting a return for it,” she told the audience, adding she has to explain to investors the company hits a lot of singles and doubles as well as home runs. “But that’s what’s fun for me. That’s what drives me.”

Kullman also talked about DuPont’s evolution as it embarks upon its third major transformation: for its first 100 years, Kullman pointed out, the company focused on explosives; in the second 100 it focused on modern chemistry; and now it’s focusing on biotech and science. “To an outsider it looks like a very different company, but the science does trail,” she said. “Science underlies all the businesses.”

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