John Travolta didn’t just learn to dance for Saturday Night Fever (1977)—he transformed himself for the role. He ran two miles a day, danced for hours every night, and trained with a former boxer who worked with Sylvester Stallone on Rocky. In roughly five months, Travolta lost 20 pounds and built the stamina needed for some of the film’s most demanding dance sequences. He even visited Brooklyn discos to study how real dancers moved. And when the studio wanted to hide his dancing with close-ups, Travolta pushed back—he wanted the audience to see that he was doing it himself. The result? Tony Manero became one of the most unforgettable dance characters in movie history—and Travolta became a global star almost overnight.