"He's recovering and already working on the telethon," his longtime manager, Claudia Marghilano, said about Lewis' benefit for the Muscular Dystrophy Association.
Lewis, 80, was released from a hospital Saturday after having surgery to insert a stent in an artery following a June 11 heart attack, she said.
He also is taking medication for pneumonia, which often strikes people with pulmonary fibrosis, a lung ailment Lewis has been fighting since 2000.
"He's had it several times. That's typical of having this lung illness," Marghilano said. "They put him on antibiotics and he's recovering. He's just doing great now."
It wasn't clear whether Lewis plans to reschedule a live performance at The Orleans hotel-casino in Las Vegas. Lewis postponed the shows set for July 13-16 after his heart attack.
Plans are still going ahead for Lewis to direct a version of his 1963 comedy, "The Nutty Professor," as a musical by next year, executive producer Ned McLeod said.
"We're excited for his recovery," McLeod said. "He's been joking with folks for several days now and warming up."
Lewis, a Las Vegas-area resident, keeps a boat in San Diego harbor.