(CNN) The women range in age from the mid-60s to the early 80s. They love to dance and sing. And twice a week, they come to a gym in Cosmo City, on the outskirts of Johannesburg, to box. They are affectionately known as South Africa's "boxing grannies," and these women are juking and jabbing their way to healthier lives.

"My life was on and off, you know -- sometimes good, sometimes bad," said 80-year-old Constance Ngubane, who's been coming in to box since the Boxing Gogos (another name for "grandmother" in South Africa) program began in 2014. "But since I started boxing ... I feel young, like I'm 16. But I'm not 16; I'm 80!"

Constance Ngubane says she feels less like her 80 years and more like age 16 when she's boxing.

For these women, boxing is as much a social activity as it is a physical one, and it is that combination that can boost the benefits of exercise. A study from the Mayo Clinic found that physical activities with more social interaction were associated with a longer lifespan.

"I love to mix with the other grannies," Ngubane said. "They are like family."

The social aspect of longevity has long fascinated researchers, gaining attention alongside more tangible measurables like diet, exercise and smoking.

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