Richard Simmons "Not Depressed", Facing "Tough Time" with Knee Injury
Richard Simmons arrives at the 2013 MTV Video Music Awards in New York August 25, 2013Reuters

Richard Simmons, the gregarious fitness guru known for his eccentric personality, who has not been seen in public for almost a year, is reportedly suffering from a knee injury.

Fans of the 66-year-old fitness instructor were concerned after reports of his absence from the public eye surfaced a few days ago. Simmons was last photographed at an event in January. Sources say that even though he is battling some health issues, he is "doing okay".

His long-time manager, Michael Catalano, told ABC News that Simmons had been sidelined with a knee injury for the past several months.

According to People, Simmons wrote on his Facebook Page: "I am so touched by the outpouring of love and concern I have received today. I have had a tough time dealing with this injury, as it is keeping me from doing what I truly love to do and that is to teach classes around the world. Make sure you keep Sweatin!" Catalano also conveyed this message to ABC News saying that Simmons had asked him to do so.

Simmons underwent a surgery for his right knee many years ago. His official website states that Simmons' 65 fitness videos and nine books helped "millions of overweight men and women lose more than three million pounds".

He has not been attending his classes at his famous Beverly Hills studio, Slimmons, for quite some time now.

Numerous reports were released recently speculating whether Simmons was battling depression and that was the reason behind his absence from the public eye. TMZ reports that Simmons needs to undergo a knee replacement surgery and if he does not do so, he might not be able to exercise ever again. Daily Mail reports that the fitness guru was afraid of the surgery and ignored it for most of the year.

He is expected to be back in action as soon as he recovers.