The actor, who has appeared on television and in movies for almost 60 years and is known for his long-running role as Dr. Victor Ehrlich on "St. Elsewhere," has been living with Parkinson's disease for years.
"I do everything the neurologist tells me to do," he said.
The 76-year-old said he began noticing symptoms long before he received a diagnosis.
"If your pinky is twitching on you, as mine was back in 1991, it might be a sign something's going on," he said. "But in another way, I'm kind of glad I didn't know that I had it until 2016. I had for many years but I was in such great shape, George, as you know, riding my bike and always exercising, always eating good, taking care of myself. So that kept it kind of underground for awhile."
Ed Begley Jr. and Hayden Begley, an actress, had long wanted to perform in a play together. They are now appearing in the Tony Award-winning and Pulitzer Prize-winning stage drama, "Proof."
The production is also serving as a fundraiser.
"One hundred percent of the proceeds from every single production goes to the Michael J. Fox Foundation," Hayden Begley said. "But if you're unable to come, you can donate through our link at Proof for Parkinson's on Instagram."
For Ed Begley Jr., the production marks his first time acting on stage in years.
"I was a young man back then, a mere 65 years of age, I think, when I last did anything like this," he said. "So I'm doing it now at nearly 77 years of age and with some challenges. But, avante, as they say in Italian. Forward! Ever onward."
Hayden Begley, whose career is in its early years, said she has long looked up to her father.
"I've admired my dad not just as my father but as a person and an artist my whole life," she said. "I mean, I've looked up to him in his activism and how he just moves about the world. And i've been lucky that not only do I have such a great role model like my dad but I'm able to recognize it."
Ed Begley Jr. and Hayden Begley are scheduled to appear in "Proof" at the El Portal Theatre in North Hollywood, California from Thursday through Sunday.