Glen Campbell is opening up about being diagnosed with Alzheimer's disease, something that certainly has not robbed the legendary performer of his sense of humor. The singer of iconic hits including 'Rhinestone Cowboy,' 'By the Time I Get to Phoenix' and 'Wichita Lineman,' along with his wife of nearly 30 years, Kim Woollen, spoke with ABC's Terry Moran for a segment on tonight's 'World News with Diane Sawyer.'

"I have been blessed, I really have," says the 75-year-old from the couple's Malibu, Calif., home. "I figured it out that I'm not that bright, but God gave me a break."

Noting that her husband has been experiencing short term memory loss for some time, Kim adds that taking care of him can be a daunting task.

"He repeats himself," she says. "Tells the same joke several times in a row."

"Well, yeah, it's funny," he remarks with a laugh.

"He'll tell a joke, laugh at it and a few minutes later tell the same joke, laugh, and then we laugh at him because he's just enjoying it so much," Kim explains. "You just make the best of each day and try not to worry about tomorrow."

"Definitely take care of what's today and tomorrow's going to have what it has," adds Glen. "There's a verse in the Bible that says, 'If the man findeth a good wife, he's found a good thing,' and I found a good thing, or she found me. Did you find me or did I find you?"

"I think we found each other," Kim responds.

"That's what we did. Amen," Glen replies.

Born the seventh son of 12 children to a sharecropper dad in Delight, Ark., Glen Campbell was given his first guitar, a $5 Sears and Roebuck model, at four years old. After joining his uncle's Western swing band as a teenager, he made the move to Los Angeles in 1958, where he became an in-demand session player and singer, initially earning just $10 a session. In 1965, Glen became Brian Wilson's on-the-road replacement in the Beach Boys. Signing with Capitol Records, he scored his first major hit with John Hartford's 'Gentle on My Mind' in 1967. By 1969, he had become an international superstar, thanks in part to his CBS television series, 'The Glen Campbell Goodtime Hour,' which ran for three years.

Other hits followed, including 'Galveston,' 'It's Only Make Believe,' and the No. 1 smash, 'Rhinestone Cowboy' in 1975. Troubles also followed, including a volatile and highly publicized romance with Tanya Tucker, and bouts of heavy drinking. He married Kim in 1981 and quit drinking cold turkey until a relapse in 2003, which led to an arrest for drunk driving.

"Thank you Lord, that's what I say," Glen notes of his sobriety and his marriage to Kim. "Thank you lord for giving me another chance."

Now, Glen is preparing to release one final album, 'Ghost on the Canvas,' due out August 30, and he's embarking his Goodbye tour to say thank-you to fans. Three of his children, Ashley on keyboards, Shannon on guitar and Cal on drums, will be joining him on stage.

"Music is a natural memory aid, and we're finding out it really does help his memory and help keep him from declining," says Kim. "So it's really good for him and all the love he gets from all the fans is really encouraging, so that's why we want to do it as long as we can, because it's healthy for all of us. Music is good medicine."

A Golden Globe nominee for his appearance in the 1970 John Wayne film, 'True Grit,' Glen Campbell was inducted into the Country Music Hall of Fame in 2005.

Watch Glen Campbell Live in Our Studio


More From TheBoot