Fitness expert and former Olympian Les Mills has died at the age of 91.

Opening a gym in Auckland with his late wife Colleen in 1968, Mills laid the foundation for what would become a nationwide chain. The Les Mills International brand is now globally recognized for its choreographed workouts set to music, including Body Pump and Body Combat.

Mills represented New Zealand in shot put and discus at four Olympic Games and later served as mayor of Auckland. His son, Phillip, noted that a common thread throughout his life was a desire to help others and that his father's "spirit lives on in gym workouts around the world."