A U.S. Marine leads training on a shooting range in France in an undated photo taken during the First World War. (Photo by Reuters/Courtesy Library of Congress)

Paramilitary policemen take part in a training in Chaohu, Anhui province, China December 28, 2015. (Photo by Reuters/China Daily)

Paramilitary policemen take part in a summer training in Shenzhen, Guangdong province, China, June 27, 2016. (Photo by Reuters/China Daily)

A line of soldiers firing handguns during a training session, circa 1920. (Photo by Keystone). P.S. All pictures are presented in high resolution.

A man sleeps in a subway train in New York city on August 1, 2024. (Photo by Charly Triballeau/AFP Photo)

National Diving School director Jerome Vincent, wearing a Gandolfi space suit, executes training procedures in a swimming pool in Marseille October 22, 2014. The underwater test session develops European expertise in spacewalk simulations under partial gravity for exploring the Moon, asteroids and Mars.The training is organised by Comex, a French company specializing in engineering and deep sea diving operations, in collaboration with the European Space Agency (ESA) and with Apollo XI “Under the sea”. (Photo by Jean-Paul Pelissier/Reuters)

Urszula Sidoruk, 19, from the paramilitary group SJS Strzelec (Shooters Association), trains her workout at a gym in Siedlce, eastern Poland March 18, 2014. Inspired by the war in Ukraine, growing numbers of Poles are joining volunteer paramilitary groups, where they receive basic army training and prepare to defend their homeland. (Photo by Kacper Pempel/Reuters)

In this picture taken on January 11, 2021, young gymnasts train at the Li Xiaoshuang Gymnastics School in Xiantao, Hubei province. This summer's delayed Tokyo Olympics, which are now due to start on July 23, 2021, will be the defining moment for Chinese gymnasts who have trained relentlessly since as young as age four in the pursuit of gold. (Photo by Nicolas Asfouri/AFP Photo)