While workouts like high-intensity interval training (HIIT) have only been popular since the early 2000s, many other types of exercise have been around much longer. Pilates , for instance, began nearly a century ago as a method of rehabilitation for injured soldiers and dancers. Yoga's origins can be traced back more than 5,000 years before that.

And we know that wrestling is older still – as famous cave paintings of the sport date back to more than 15,000 years ago. Tai chi began more recently than that, but is still considered to be an ancient practice because it was started by a Taoist monk who lived around 1300 AD. It's also something still many practice today – and for good reason.

What is tai chi? Tai chi is a yoga-like practice that involves a series of slow, gentle movements and physical postures, a meditative state of mind and controlled breathing , per the U.S. National Center for Complimentary and Integrative Health (NCCIH).

While we know that tai chi originated anciently from martial arts in China, over the years the exercise has become more focused on health promotion and rehabilitation. This is because tai chi has been at the center of more than 500 published medical studies . It's a body of "credible medical research that has catalyzed tai chi's popularity in the West," notes Peter Wayne, director of the Osher Center for Integrative Medicine at Harvard Medical School and at Brigham and Women’s Hospital in Massachusetts.

Indeed, today "tai chi is a practic.