Fitness guru Richard Simmons has died, two law enforcement sources confirmed to NBC News. Simmons was found unresponsive Saturday at his Hollywood Hills home, one day after his 76th birthday, the law enforcement sources said. The exact cause of his death is pending.

On Friday, Simmons shared a message on social media thanking fans for the birthday wishes. Know the news with the 7NEWS app: Download today “Thank you..

.I never got so many messages about my birthday in my life!” Simmons wrote. “I am sitting here writing emails.

Have a most beautiful rest of your Friday.” He signed the post “Love, Richard.” Simmons, the fitness coach known for his eccentric personality and “Sweatin’ to the Oldies” workout videos, rose to fame in the 1970s and 1980s after opening a number of gyms and releasing dozens of fitness videos.

His website describes him as “one of the world’s most revered and iconic fitness personalities” who has been an “instructor and motivator for over 40 years.” “By delivering a serious message with his trademark humour, he has helped millions of overweight men and women lose more than 3,000,000 pounds by adopting sensible, balanced eating programs and exercise regimes that are energetic, fun and motivating,” a biography for Simmons on his website reads. Simmons grew up in New Orleans and weighed 268 pounds when he graduated from high school, according to his website, which added that he “took control of his weight” by changing his li.