Yu Jing, expressway toll collector, Anhui province

Yu Jing, 27, an expressway toll collector in Anqing, Anhui province, said she was proud of all the friendly smiles she had shared over the past six years, even though people seldom knew her name. She said she feels the smiles made a difference.

Yu leans out the window of her booth to take a toll card handed up by a driver. She states the toll sum, takes cash or guides a driver making a mobile payment. As she returns the invoice, she wishes every driver a happy journey and life.

During her eight-hour daily work shift, Yu keeps smiling as long as drivers can see her face.

The simple smile effectively improves travelers' experience, reducing conflicts and even accidents.

"Working in our small booths, each of us may encounter hundreds or thousands of people every day," Yu said. "If smiling were not a must, we might find ourselves displaying negative emotions sometimes, and it would be sad to make customers feel bad."

Instead, many drivers now greet her in a friendly way, sometimes praising her professionalism with a compliment or thumbs-up, she said. The positive feelings go both ways. "I become happier when I know the drivers are happy," she added.