Retired army members take part in a laughing yoga session ahead of 2017 World Laughing Day. Studies have shown that mirthful laughter, the kind that stems from real joy, relieves stress, lightens mood and confers health benefits.
Sunil Ghosh/Hindustan Times via Getty Images
Goat yoga participants try to stay in a yoga pose as a young goat walks over them at the Welcome Home Ranch in Arizona.
Ross D. Franklin/AP
Stephanie Moser, second from right, hoops during an evening hooping class in Pittsburgh. Hula hooping has become hip again, with clubs across the US bringing together hoop aficionados and DVDs incorporating hoops as a way to fight obesity.
Gene J. Puskar/AP
Atiya Hodges, center, teaches a pole dancing class at Taboo Dance & Fitness in Bowling Green, Kentucky. Experts say the class is a demanding one that requires skill and technique, which in turn uses energy.
Bac Totrong/Daily News via AP
People enjoy aerial yoga using hammocks suspended from the ceiling in Tokyo. The trend is also called antigravity yoga.
Kunihiko Miura/The Yomiuri Shimbun via AP
Trampolining is another class gaining popularity, promising an active and intense workout.
Pat Greenhouse/The Boston Globe via Getty Images
Women practice swimming with mermaid tails at AquaMermaid swimming school in Chicago. Fitness experts believe any class engaging people in long-lost passions or curiosities will benefit the health of a population.