It's a lesson that dozens of fashion-conscious performers took to heart, singing and stomping across the main stage in a dazzling array of leotards, lace, crop tops and otherwise theatrical elements.
Florence Welch chose a lace leotard with a billowing tiered tulle sleeve, custom designed for her Glastonbury performance by Maison Martin Margiela. Look closely, and you can see the 1950s prom dress it once was - it took the Maison 29 hours to adapt the vintage piece into the stage outfit!
Paloma Faith looked every inch the circus performer/glittery aviatrix in her ensemble, a long-sleeved embellished ivory leotard with matching suspenders, gold leather heels, a helmet-like cap - and a harness attached to two giant weather balloons.
Kylie completed the leotard triumvirate in a black, lace-panelled item with billowing chiffon sleeves. Mirror-embellished thigh-high boots in the summer? That's why we love her...
Even performers who missed the leotard memo raised their fashion game. Bulletproof singer La Roux wore a sculptural Viktor & Rolf jacket just a few days after playing the Dutch design duo's menswear show in Paris.
With Shakira, it was less what she was wearing than what she wasn't - the crowd went wild when the bendy Colombian singer tied up her skull-print vest to expose her toned tummy for some She Wolf belly dancing. Hips? Lie? Never.