We may still go Sweatin’ to the Oldies after this, but it won’t be nearly as much fun anymore: General Hospital alum Richard Simmons, arguably the most famous celebrity fitness instructor of all time — sorry, Jane Fonda — has died at age 76.

Born Milton Teagle Simmons, the future fitness buff rose to fame in the 1970s as he dropped 123 lbs. and sought to help others lose weight as he had. Once the media took notice of his boisterous personality, he began getting booked on game shows, which eventually led to him being cast as himself on General Hospital.

This was no in-and-out guest gig, either. From 1979-82, Simmons recurred on the soap and taught exercise classes, first at the Campus Disco, then at the Community Sports Center. More than 20 years later, he returned to Port Charles for the Nurses Ball — and, of course, to continue to get under the skin of frenemy Lucy Coe.

Simmons was known to personally interact with his fans — a lot. When he was on General Hospital, he responded to countless messages and even made phone calls to those who were trying to shed a few, or quite a few, pounds. After 2014, the onetime host of The Richard Simmons Show retired from public life, which, ironically, only made the press more curious about where he was and what he was doing.

Reportedly of natural causes, Simmons drew his last breath on July 13, only a day after he turned 76.