Eclectic fitness guru Richard Simmons has died at the age of 76, according to his representative. Police officers and firefighters responded to his Los Angeles home after they received a call from his housekeeper on Saturday just before 10 a.m., law enforcement sources told TMZ. He was reportedly pronounced dead at the scene. Simmons cause of death was not immediately clear. Authorities believe he died of natural causes and do not suspect foul play at this time. He had just celebrated his 76th birthday on Friday. The shocking news comes after Simmons worried fans with a cryptic Facebook messag…