Competitors take part in the Christmas Really Wild Mud Run on a 4.6 miles course across undulating farm land at Celtic Camping, St David's, Pembrokeshire, Wales, December 12, 2015. (Photo by Rebecca Naden/Reuters)

Participants take part in the Color Run near the Eiffel Tower in Paris April 19, 2015. The Color Run is a five-kilometre race, held in cities across the U.S. and also worldwide, with the aim of promoting healthy living and to benefit a charity that organizers choose in each of the cities that the run visits. Participants are doused from head to toe in different colors at each kilometre. (Photo by Benoit Tessier/Reuters)

This picture taken on February 23, 2014 shows participants wearing dresses running half-naked in the annual 3.5 km Undie Run held in the Olympic Forest Park smog-covered Beijing. Some 200 participants took part in this event, many of them with gas masks, as dangerous smog blighted swathes of northern China in recent days. (Photo by AFP Photo/STR)

Participants climb a 10km muddy obstacle course during the “Run Mud” race, on March 29, 2019 in the Israeli mediterranean coastal city of Tel Aviv. Over 6,000 participants took part in the obstacle race, with up to 18 artificial obstacles on three tracks (10 km, five km or two km). (Photo by Jack Guez/AFP Photo)

“Asaro from the Eastern Highlands”. The mudmen could not cover their faces with mud because the people of Papua New Guinea thought that the mud from the Asaro river was poisonous. So instead of covering their faces with this alleged poison, they made masks from pebbles that they heated and water from the waterfall, with unusual designs such as long or very short ears either going down to the chin or sticking up at the top, long joined eyebrows attached to the top of the ears, horns and sideways mouths. (Photo and caption by Jimmy Nelson)

“The last known individual of the subspecies was a male named Lonesome George (Spanish: El Solitario Jorge/George), who died on 24 June 2012. In his last years, he was known as the rarest creature in the world. George served as a potent symbol for conservation efforts in the Galápagos and internationally”. – Wikipedia. (Photo by Rodrigo Buendia/AFP)

Competitors in costume cross a water obstacle during the Wildsau Dirt Run (Wild Boar Dirt Run) obstacle course fun race at Hellsklamm ravine in Obertriesting, Austria, October 22, 2016. (Photo by Heinz-Peter Bader/Reuters)

A participants mends his vintage car during the annual London to Brighton veteran car run in London, Britain November 6, 2016. Around 600 classic cars took part in the annual 60 mile journey to the south coast resort. (Photo by Neil Hall/Reuters)