Walmart International CEO Judith McKenna previously served as COO of Walmart U.S., a job that had her oversee its massive U.S. workforce and its enormous store footprint.

It would be easy to become overwhelmed by that size, but McKenna told the executives in attendance at Fortune’s Most Powerful Women Summit on Wednesday that she thought about the business—that was in need of “reenergizing” at the time—in chunks. “Simplicity,” she said, is the only thing that works when you’re dealing with a business that big.

McKenna assumed her current role at Walmart International in February, and in her first few months on the job Walmart sold the majority stake of its Brazil business, struck a deal between its U.K. Asda arm and British grocer Sainsbury, and bought a 77% stake in India’s biggest online retailer Flipkart. Her new job has its own massive scale, but McKenna still sweats the small stuff—”TNTs,” as she calls them, for tiny, noticeable things.

“What makes a difference sometimes is not big things but TNTs,” she said on Wednesday. An encouraging note, a congratulatory phone call, conversations with behind-the-scenes workers—those gestures can “make a real difference,” McKenna said.

“At the end of the day,” she said, “all of these jobs are about people.”

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