"Richard Simmons was hospitalized on Monday at an undisclosed location in California," Simmons' rep, Michael Catalano, tells ET.
"After a few days of battling severe indigestion and discomfort while eating, we agreed it was best for him to seek treatment."
"He's already feeling better and is expected to make a full recovery," he adds.
The 68-year-old fitness icon has shied away from the public eye over the past few years, but earlier this month, Catalano announced that his management company, Prominent Brand + Talent, had acquired exclusive rights to represent Simmons for merchandising, endorsements and licensing opportunities.
In a statement to ET, Catalano said that the yet-to-be-released products would be "consistent" with Simmons' "message and mission."
Simmons' disappearance from public life even recently inspired a podcast, Missing Richard Simmons.
In an exclusive phone interview with ET in 2016, Simmons addressed the fascination over his new private life and said, "no one should be worried about me."
"I love all the people who worry about me," Simmons said.
"But it was time for me to take some time to be by myself. For the last 40 years I have been traveling, teaching classes, and I had a knee injury, so I had a knee replacement, which was very difficult for me… I have really just been taking it easy, staying at home, working out in my gym and doing the things I haven't done in a very long time."