LOS ANGELES (AP) — Congratulate Bob Newhart on turning 90 on Thursday, and he offers a polite critique in return.

“I’m not crazy about the term ‘turning,’” he says, chuckling. “Sounds like the leaves are going to fall off. I’m becoming 90.”

As is true of the best comedians, Newhart is an impeccable wordsmith and has the career highlights and enduring success to prove his mastery. An inarguable description of Newhart’s precise and singularly droll take on life: ageless.

“The Button-Down Mind Of Bob Newhart,” released in 1960, was the first comedy record to hit No. 1 on the Billboard pop album chart and made him the only standup, still, to win a Grammy as best new artist. He scored TV hits with “The Bob Newhart Show” in the 1970s and “Newhart” in the ’80s, and delighted 21st-century viewers with his Emmy-winning turn as Professor Proton on “The Big Bang Theory.”

The typed page of his famed bit in which President Abraham Lincoln gets image advice from a marketing consultant is going into the Smithsonian’s popular culture collection.

Work keeps coming his way, including requests to mark his birthday on stage. But he decided he’d rather spend the day with his wife of 56 years, Ginnie, and their family. The Chicago-area native talked about his staying power and early career to The Associated Press, with the interview edited for clarity and length.

AP: When someone reaches an impressive milestone birthday, there’s an obligation to share tips with the rest of us hoping to get there.

Newhart: I’ve said it before, but of all the weird things, comedians’ marriages seem to last the longest: George Burns and Jack Benny and Buddy Hackett and (Bob) Hope. I think there’s something between longevity and laughter. You’ll be having a fight, and you’ll say something stupid and then start to laugh, and then she’ll start to laugh, and then the fight’s over. I think laughter is vital. It’s as vital as breathing. It gets you through difficult areas. Laughter is one of the most beautiful sounds in the world. It’s like music, of a kind.

AP: Is that part of what’s kept you working for so long?

Newhart: I’m amazed at the longevity. The album had just come out, and I was just learning how to do standup and I was the opening act for Peggy Lee at the Harrah’s club in Lake Tahoe. I had 15 minutes of material and I did it, and the stage manager said, “Go back out. They’re applauding.” I said that’s all I had, and he said, “They’re applauding.” So I went back out and asked, “Which one do you want to hear again?” and they yelled out what they wanted. That’s how raw I was. I had a hit record and I was just starting out. I had to learn my craft backward.

AP: You started out as an accountant. Is it hard to imagine that might have been your life?

Newhart: I played a club before the album came out, and they (the audience) had no idea who I was and I died, every night. Not a snicker. You could hear the air conditioning. I would have welcomed a cough, just some sound coming from the audience. Every comedian in the world has gone through that. We did two shows a night, seven days a week, and that’s about the time that accounting started to look really good to me. Then I played at another club, in Winnipeg (Canada), and it went well. And I thought, maybe I’ll stick around for a while.

AP: Do you have an all-time favorite bit, maybe Lincoln?

Newhart: That was Jack Benny’s favorite. I always felt Abe was the best piece of writing I ever did. It’s probably more true today than it was in 1960 when I recorded it. You see the machinations going on now. I read a book back then, Vance Packard’s “The Hidden Persuaders,” about subliminal advertising and packaging a product, including presidents. That’s what we’re all watching right now, the packaging. It’s the same way they package soap.