Gamma-Keystone via Getty Images

Who: Muhammad Ali

When: May 11, 1966

Where: Royal Artillery Gymnasium, London

Why: If Rocky Balboa's the boxer who made head-to-toe sweats famous, Muhammad Ali made them cool in the first place, something we're arguing based solely on the photo above and our fair assumption that the GOAT's reign also applies to everything he wore (satin shorts included). While training for his 1966 bout against British boxer Henry Cooper, Ali here proves that even the most basic, no-frills sweats can become something much cooler with a little (or, in his case, a lot) of applied swagger. And let's not forget that back then, they were somewhere closer to government-regulation clothing than any sort of fashion statement. Just check out that perfectly frayed sleeveless shirt. In reality, it's a sweatshirt with the sleeves cut off(!), a move you can easily do yourself and something that Ali probably did on his own—that, or he just ripped them clean off in Hulk-like fashion. This photo proves you don't need luxury sweatpants to look cool or get swole at the gym. In this D.I.Y. day and age, you just need to make sure you've made it your own.

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