Alan Alda has Parkinson's disease. In an appearance on "CBS This Morning" Tuesday, the award-winning actor, best known for his relatable portrayal of Army Capt. "Hawkeye" Pierce in the TV series "M*A*S*H," revealed he was diagnosed three-and-a-half years ago.

"I've had a full life since then," he said. "I've acted, I've given talks, I help at the Alda Center for Communicating Science at Stony Brook. I started this new podcast. And I noticed that – I had been on television a lot in the last couple of weeks talking about the new podcast – and I could see my thumb twitch in some shots and I thought, it's probably only a matter of time before somebody does a story about this from a sad point of view, but that's not where I am."

Alda said he got tested for the disease after reading an article about how one of the early signs of Parkinson's is acting out dreams. 

"I was having a dream that someone was attacking me and I threw a sack of potatoes at them. But what I was really doing was throwing a pillow at my wife," he said.

The 82-year-old recently launched a podcast called Clear+Vivid, which explores all the ways in which people communicate with each other. The ability to engage with people clearly, he says, is the key to greater understanding for everyone. Another reason Alda spoke out was to send a message of hope to those who might be facing the disease.

"In the very beginning, to be immobilized by fear and think the worst thing has happened to you – it hasn't happened to you. You still have things you can do," Alda said. "I'm taking boxing lessons three times a week. I do singles tennis a couple of times a week. I march to Sousa music because marching to music is good for Parkinson's."

Perhaps one of the best-known people with Parkinson's is actor Michael J. Fox, who went public with his diagnosis nearly two decades ago.

Despite the prospect of severe, life-altering symptoms, Alda says he's "not angry."

"Because it's a challenge, you know? You've got to cross the street, there are cars coming. How do you get across the street? You don't just sit on the pavement and say, well, I guess I'll never cross the street again. You find a way to do it," Alda said. "There are some common symptoms, but mostly everybody's different and each day is different from the next. One day you wake up, you think, oh, it's over, it's gone. Next day it's back a little worse. You don't know what it's going to be, but the main thing is, there's stuff you can do and I've been -- you know how I look at it? It's like a puzzle to be solved. What do I have to adapt to to carry on a normal life? And I enjoy solving puzzles."

Through the Alan Alda Center for Communicating Science, he teaches acting techniques to scientists and entrepreneurs to help them connect better with their audiences.

"It would be kind of ironic if I kept quiet about this when a center for communicating science is named after me. But I think because I'm sort of well-known, it might be helpful to people to hear the message that there are things you can do. You can learn about things and not follow quackery, but find out what real science is coming up with. That helps. It helps to keep moving. It helps to move rhythmically," Alda said.

He hopes by going public to not just ease the fear others might be feeling, but to also put his own mind at ease.

"I'm not going to worry. While I'm trying to say something else, I'm not going to be thinking, is my thumb on a life of its own. You know, that's just one of the realities of my life. But I've acted in movies since – it's three-and-a-half years since I had the diagnosis and it hasn't stopped my life at all. I've had a richer life than I've had up until now."