But somewhere along the way, he discovered the ancient exercise and breathing regimen developed by Chinese Taoists many centuries ago. Since being introduced to by fellow cancer survivors at a rehabilitation centre, Zou practices every morning in Mengqing Park near his home.

Now, the 72-year-old attributes his current state of well-being to the practice. Zou recalls catching a cold only once in the past four years.

Zou said the park, with its pond and many trees that make the air seem fresher, gives him a feeling of "peaceful alertness and physical vitality".

Public parks on the mainland buzz with activity all day from early morning. Chinese chess and card players vie for space on park benches with young couples and elderly pensioners. Groups of fan dancers, students and ballroom dancers follow the lead of their master, or .

Many, like Zou, practice which was curbed during the central government's crackdown on the Falun Gong, who practised a variation and were deemed a cult in the 1990s.

Today, now the ban has been relaxed, different styles of practice are classified as martial, medical and spiritual. All have three things in common: various physical postures, breathing techniques and mental focus or meditation.

Although Shanghai witnessed a spike in health services providers in the past decade, is still widely practised - in some cases as an alternative or complementary medical treatment.

Some practitioners believe the breathing techniques and slow, meditative movements are more effective than conventional medicine in treating certain ailments and diseases.

Gu Huifen, 58, said she turned to in November when she became alarmed about her declining health. Gu had her gall bladder removed several years ago, and suffers inflammation and pain around her liver.

"I tried Western medicine and ate herbs [used in] traditional Chinese medicine, but they couldn't relieve my pain," Gu said. "I was so frail that my friends jokingly said that a puff of wind could knock me over."

As she regains her strength and experiences less pain, Gu is gaining confidence in her ability to recover.

Like many forms of alternative medicine, has attracted its share of charlatans and con artists. Wang Lin, a self-proclaimed master who professed to have supernatural powers, was investigated by police in Jiangxi in August for various crimes including fraud.

Practitioners are not put off by such scandals. Xu Feng, vice-director of the Shanghai Qigong Research Institute, said the ancient practice might invest practitioners with mysterious powers but that its underlying philosophy was still being studied.

"We aren't keen to publicise mysterious [ ] abilities that science can't explain," Xu said.