BEIJING — Before cranking up the techno at his 80th birthday party, the man known as China’s hottest grandpa paused from his disc jockey duties to poke fun at the staid traditional celebrations for the elderly in a country that venerates old age.

“I should wear a long robe, with the word ‘longevity’ embroidered on the front,’’ the birthday boy, Wang Deshun, said at his party in September. Far from looking old and frail, the silver-haired actor, model, and artist wore a crisp white shirt and black jeans, his back straight and his eyes glittering with humor. “Two young maidens should help me into an old-style wooden chair,’’ he continued, pretending to dodder. “On a table in front of me there should be peaches,’’ a symbol of longevity, “and my students should kowtow, wishing me a good birthday.’’

“So, what am I doing today? My students from 30 years ago are putting on a fashion show, and I’m the DJ,’’ he said, signaling the start of the show with a thudding techno mix.

Determined to avoid mental and physical stagnation, Wang has constantly explored new skills and ideas while devoting ample time to daily exercise. Last year, at 79, he walked the runway for the first time, his physique at his age causing a national sensation. He takes obvious joy in subverting China’s image of what it means to be old.

And old age in China begins relatively early. The legal retirement age for women is 50 for workers and 55 for civil servants, and 60 for most men. Wang is having none of that.

“One way to tell if you’re old or not is to ask yourself, Do you dare try something you’ve never done before?’’ he said.

“It’s about your state of mind. It’s not about age. Nature determines age, but you determine your state of mind.’’

Being older in China typically means being respected, but also, often, sentimentalized. Someone as young as 50 may be addressed as “yeye’’ or “nainai’’ — grandpa or grandma — regardless of whether they have offspring. Retirement homes are known as “respect elder homes.’’

Wang has not escaped being called grandpa — he has two children and a 2-year-old granddaughter — but the honorific is accompanied by accolades for his vigor and embrace of the new. “Grandpa, you’re my idol!’’ one admirer wrote on Wang’s Weibo social media account, one of thousands of such comments.

Sex appeal is part of the mix, too. “Grandpa, your stomach is so gorgeous! Incredibly handsome!’’ another person wrote next to a photo of Wang topless in a gym, his skin smooth and pectorals buff.

“China’s hottest grandpa,’’ as many call him, said he was always athletic. An avid swimmer as a child, he still swims more than half a mile each day. “Morning is my learning time,’’ he said. “I read books and news. From 3 to 6 p.m. is my exercise time, in a gym near my home.’’

He also drinks less alcohol now, he said, but that is about as far as his dietary restrictions go. “I am not picky at all about what I eat. I eat whatever I want to eat.’’

His regimen may not work for everyone, but his enthusiasm for staying active is seen by some as a good example.

“Mr. Wang’s attitude is very much needed today,’’ said Lu Jiehua, a sociologist at Peking University.

“Many old people drop contact with the outside world and curtail their involvement in society, which is dangerous,’’ Lu said in an interview.

Wang is a phenomenon not just for his physicality — notable in a society where men rarely highlight their beauty — but also for the example he sets in a society that is growing older fast.

“People can change their life as many times as they wish,’’ he said.