Fitness guru Richard Simmons died Saturday at the age of 76, his representative and law enforcement sources confirmed to multiple media outlets. Simmons had just celebrated his birthday on Friday and had posted a thank you on social media for all of the messages, less than 24 hours before his death. Law enforcement sources confirmed to NBC News that Simmons was found unresponsive Saturday at his Hollywood Hills home. A representative for Simmons confirmed the fitness icon's death to ABC News. Read the latest at the link in our bio. #richardsimmons