Billy Joel's daughter Alexa Ray Joel is sharing an update on the singer's health after he was diagnosed with a brain disorder nearly one year ago. "He's doing physical therapy regularly and he's doing great. He's lost weight as he's on his diet," Alexa, 40, told The Hollywood Reporter in an interview published on Thursday, March 12. "I'm so proud of him. He's such a trooper, so resilient and committed to being healthy and proactive. He's a fighter. He's always been a fighter and talks in his documentary about how life's like a fight.