HARBIN－With her silver hair, 68-year-old Xu Lili stands out in a crowd of young people.

Xu goes square dancing every night with her friends in the center of Harbin, Northeast China's Heilongjiang province. Their dancing has strong rhythm and a wide range of movements, making it more like disco than the slow traditional Chinese square dancing. Xu is the organizer and the only senior taking part.

Apart from Xu, most dancers are in their 20s. "Grandma Xu may be old, but we all learn from her," says Zhang Dongkai, 23. "She is our leader."

"Most of my friends are young people. I have danced with them for more than 10 years. I can't do that kind of slow dance," Xu says, adding that dancing is the happiest part of her day. It not only keeps her fit, but also makes her happy.

The contrast between her age and her dancing has not only endeared her to those around her, but also made her famous online, with many netizens praising her dancing and optimistic attitude.

Instead of just looking after grandchildren, increasing numbers of elderly Chinese are enjoying their own lives.

Wang Yun, 72, goes to a dance class for seniors every week at Harbin University, which was founded in 1984 and is one of the earliest universities for the elderly in China. Hundreds of thousands have graduated from the institution over the past three decades.

The average age of Wang's dance class is over 60. Teacher Li Yongxia says she has taught dance there for more than 10 years. Many students were not in good shape when they first came, but dancing changed their attitude toward life.

Harbin University for the elderly is very popular. Though there are branch schools in every district of Harbin, many courses are full soon after the online registration channels are opened.

Qu Wenyong, a sociology professor at Heilongjiang University who has been following the elderly care industry for many years, says the ages from 60 to 70 have become part of the "golden decade" for China's elderly as the country's average life expectancy increases. "They are healthy, they have time and they demand a higher quality of life," Qu says.

Many elderly people in China also like to share their lives on the internet.

Not long ago, a video of 66-year-old Deng Xiaohui walking a catwalk with her partner in Harbin's Central Street received more than 1 million likes on social media.

"I loved fashion shows when I was young, and I realized my dream after I retired." Deng has been studying the catwalk for five years at a modeling school in Harbin.

Wang Deshun, 86, is known to many netizens in China. He started working out at 50, and walked the runways of China Fashion Week at 79.