Like Walmart's (WMT) founder Sam Walton, the retailer's U.S. president and CEO likes to drop in unannounced.

Greg Foran explained recently why he makes frequent store visits—without warning— in order to check in on the nearly 4,700 locations, which employ more than 1 million associates.

"I think it is a critical part of the job, isn't it?" Greg Foran told Yahoo Finance during one such store visit, just ahead of Walmart’s annual shareholders meeting in northwest Arkansas.

"Because it's actually where the rubber hits the road in our business. And we're only as good as the last transaction that we had with the customer,” he added.

There are many things Foran looks for before arriving on site, including seemingly small things like the parking lot and store rooms

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"I usually start looking at the neighborhood as we drive up to the store,” he said. Also, “I always travel around the store before I actually even enter it to see how tidy are we at the back, are we stacking the pallets, are the cardboard bales being picked up?"

During Foran's tenure, he's focused heavily on improving the quality of the fresh food department, since it's one of the first areas customers encounter, in addition to the overall in-store experience.

He checks virtually every detail, from store associates down to lighting and the smell of fresh produce.

"And I just love doing that. And I know that you know, the better that we get at doing that, the better the experience is for the customer,” Foran said.

The executive, who typically sports a casual look at work, is sometimes mistaken as a store associate and when that happens he smiles and serves the customer.

"And that really is one of the first things that we want our associates to do — is to engage with our customers, be really happy with the job that we're doing. And then deal with whatever questions or queries that they've got in a really efficient manner,” Foran added.

Advice for associates

The 58 year-old got his start in the retail industry as a teenager at Woolworths, the leading supermarket in Australia and New Zealand.

During 30 years, he held several roles at Woolworths. Just months after being passed over for CEO, he left the company in July 2011.

Foran joined Walmart in October 2011 and became CEO of Walmart China in 2012 and CEO of Walmart Asia in early 2014. He was tapped to lead the U.S. business in July 2014.

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His advice for associates? "Whatever job you're doing, do it to your very best of your ability,” he said.