Participants compete during the Strong Race event near Tukums, Latvia, May 3, 2015. More than 4,000 people participated in this 9 km endurance race with 33 different obstacles. (Photo by Ints Kalnins/Reuters)

Participants stretch their bodies as they pose for pictures before the Beijing International Marathon in Beijing, China, September 20, 2015. About 30,000 runners participated in the annual running event. (Photo by Kim Kyung-Hoon/Reuters)

This picture taken on January 25, 2015 shows a participant taking part in an ice water challenge in Zhangjiajie, central China's Hunan province. Participants were required to stay in an ice pond, holding an ice block while eating ice-cream with an electric fan blowing at them. (Photo by AFP Photo/Stringer)

A girl participates in a New Year calligraphy contest in Tokyo, Japan, January 5, 2017. (Photo by Kim Kyung-Hoon/Reuters)

A participant in costume uses a mobile phone at a Halloween event in Kawasaki, south of Tokyo, Japan October 29, 2017. (Photo by Kim Kyung-Hoon/Reuters)

A participant runs through foam during the Love Foam Run race in Hsinchu, Taiwan May 29, 2016. (Photo by Tyrone Siu/Reuters)

A couple participates in the “Running of the Brides” race in a park in Bangkok, Thailand on March 25, 2017. (Photo by Athit Perawongmetha/Reuters)

A participant wearing a costume and make-up attends a Halloween parade at Walibi park in Wavre, Belgium, October 25, 2019. (Photo by Yves Herman/Reuters)