Women practice swimming with mermaid tails at AquaMermaid swimming school, a mermaid training school in Chicago, United States on March 19, 2017. Participants are fulfilling their lifelong ambitions of becoming mermaids with a new type of fitness mermaid swimming. (Photo by Bilgin S. Amaz/Anadolu Agency/Getty Images)

These images of young children training were taken at a gymnastics summer camp in Bozhou, Anhui province, China on July 28, 2015. Children with promise are selected to attend, and their families hope training will not only benefit their children physically but also increase ‘willpower’, according to China News Service. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)

A surfer dressed as Santa gets to his feet as he braves the cold seas and near flat waves during the annual Surfing Santa as part of the Santa Run and Surf 2016 at Fistral Beach in Newquay on December 4, 2016 in Cornwall, England. Now in its third year, the santa surf and fun run is organised by Fistral Surf Center and Cornwall Hospice Care and raises funds for local charities. (Photo by Matt Cardy/Getty Images)

Santa Claus rides in his sleigh as he prepares for Christmas in the Arctic Circle near Rovaniemi, Finland December 15, 2016. At Santa Claus' Lapland home in Finland, his helpers sort out piles of letters from around the world, each detailing children's requests for this Christmas. (Photo by Pawel Kopczynski/Reuters)

A girl looks at other children practicing on a boxing ring during an exercise session at a boxing school, in the Mare favela of Rio de Janeiro, Brazil, June 2, 2016. For many young residents the Luta Pela Paz (Fight For Peace) academy offers a glimpse of an alternative: a chance to build discipline and self-esteem through boxing and martial arts. (Photo by Nacho Doce/Reuters)

Children attend a swim training session at Hangzhou Chen Jinglun Sport school Natatorium, where Chinese Olympic swimmer Sun Yang and Fu Yuanhui also trained, in Hangzhou, Zhejiang province, China, August 10, 2016. (Photo by Aly Song/Reuters)

Students carry a female trainee who has fallen into a stupor during high intensity training at Tianjiao Special Guard/Security Consultant camp on the outskirts of Beijing December 1, 2013. Former Chinese soldier Chen Yongqing has big ambitions for his bodyguard training school Tianjiao, which he says is China's first professional academy to train former soldiers and others as personal security guards. Chen charges 500,000 yuan ($82,400) a year for each protector as China's rich and famous look to bolster their safety and sense of importance. (Photo by Jason Lee/Reuters)