Migrant workers and their families board an overcrowded passenger train, after government imposed restrictions on public gatherings in attempts to prevent spread of coronavirus disease (COVID-19), in Mumbai, India, March 21, 2020. (Photo by Prashant Waydande/Reuters)

In this Thursday, June 14, 2018, file photo, students wear virtual reality goggles during a science class at Pyongyang Teachers' University, a teacher training college, in Pyongyang, North Korea. (Photo by Dita Alangkara/AP Photo)

Professional dancer Sandy Lewis, from Louisiana, performs with his dance partner Marti Gasol, as they train in the street due to restrictions to do it indoor, in Barcelona on Wednesday, November 11, 2020 as Spain continue with new measures against the COVID-19. (Photo by Emilio Morenatti/AP Photo)

Soldiers of People's Liberation Army (PLA) Lanzhou Military Region jump through a burning obstacle during a training session at a military base in Tianshui, Gansu province, China, January 6, 2016. (Photo by Reuters/Stringer)

An Israeli teenager crawls through mud as he participates in an annual combat fitness training competition, as part of his preparations ahead of his compulsory army service, near Kibbutz Yakum, central Israel February 19, 2016. (Photo by Baz Ratner/Reuters)

A train drives along a field at a salt production site at the Sasyk-Sivash lake near the city of Yevpatoria, Crimea, November 14, 2017. A saltwater lagoon known as Lake Sasyk-Sivash on Ukraine's Crimea peninsula is the source of a rare resource: pink salt. The mineral is tinted by tiny algae that produce the pigment beta-carotene. Each autumn, seasonal workers collect thousands of tons of pink salt for processing and export. (Photo by Pavel Rebrov/Reuters)

In this November 20, 2017 photo, Indian kushti wrestlers fight in the ring, during their daily training at an akhada, a kind of wrestling hostel at Sabzi Mandi, in New Delhi, India. Like many traditions in rapidly modernizing India, kushti wrestling faces the threat of being left behind. But for many poor families, the ancient sport provides a glimmer of hope. (Photo by Dar Yasin/AP Photo)

Martin Herrera, 58, who has had a love for roosters since his childhood, and has spent the last 20 years domesticating and training them, walks with his favorite rooster “Paquito” in San Jose, Costa Rica April 27, 2017. (Photo by Juan Carlos Ulate/Reuters)