She was dubbed "the world's greatest athlete" after taking decathlon gold at the 1976 Olympics and becoming an overnight American hero.
But the former Bruce Jenner - now Caitlyn Jenner after becoming a transgender woman - says she works harder at her make-up than she ever did at winning gold.
Writing in her new autobiography, serialised in You magazine, Jenner reveals: "Applying make-up is always intense and I sometimes think I work harder on it than I did to win the decathlon.
"I secretly bought how-to books since there was nobody to help me."
She also reveals how she stole clothes and make-up from her wife Kris, and her daughters and stepdaughters, including Kim Kardashian, whom she has starred with in the hit American reality TV series Keeping Up With The Kardashians.