At age 90, legendary actress Betty White is juggling a packed schedule. In addition to participating in public-speaking events in support of animal welfare, she’s starring in two TV series (“Hot in Cleveland” and “Betty White’s Off Their Rockers!”) and recently published “Betty & Friends: My Life at the Zoo.” White speaks Thursday at the Smithsonian Associates program “Betty White’s Animal Instincts” at Lisner Auditorium and will swing by the National Zoo Friday for a book signing. (Both events are sold out, but there is a wait list for Thursday’s event, and more tickets may be released.)

You’re so busy. How do you find time to sleep?
I don’t require a lot of sleep. I’m never ever in bed before midnight and I’m up at 6 every morning. If I get four, four and a half good solid hours, I’m good.

When did you become an animal activist? 
I’m not an activist. I’m an advocate for animal welfare. I don’t get political.

What inspired your advocacy?
It was two animals: my mother and my father. My love of animals started in the womb. It’s always been my fascination.

How do you react when you hear about cruelty to animals?
The human animal is not the most humane animal in the world. There are people who get a kick out of being cruel, not only to animals but to kids and to each other. I just don’t understand. It’s mind-boggling how they can live with themselves.

You have a great TV persona — nice yet naughty.
I’m afraid I have a rather bawdy sense of humor. But I don’t like dirty jokes. I enjoy double meanings.

What’s it like being 90?

You don’t feel the age. It sneaks up on you and all of a sudden the calendar tells you [you’re 90]. But I don’t feel any different now than when I was 50. I’m blessed with good health. It’s awfully easy to enjoy old age if you’re not feeling rotten.

An indiscreet question: There’s supposedly a nude photo of you from years ago circulating on the Internet. Is it real?
Somebody put that together. I think that’s going a little bit too far. I was really upset about it. I never posed nude in my life. And my problem is that if I had posed nude, I’d just get laughs.

I don’t know — my young colleagues were excited when I told them I was going to speak with you.
They just dig old ladies.

Backstory: Betty White got her start in acting in the late 1930s and landed her own radio show, “The Betty White Show,” in the late ’40s. Two televised incarnations of the series followed, one from 1954-1958 and another from 1977-1978. She’s won seven Emmy Awards for her work.

National Zoo, 3001 Connecticut Ave. NW; Fri., 12:30 p.m., sold out; 202-633-4800. (Woodley Park)