Barbra Streisand talked about her new memoir in a pair of interviews with the Associated Press and Variety.

The singer and actor’s My Name Is Barbra, published last month by Viking, became an instant bestseller upon its release. In a starred review, a critic for Kirkus wrote of the book, “What a talent, what a career, what a life, and what a treat to relive it all with this most down-to-earth of demigods.”

In an interview with Hillel Italie of the AP, Streisand said writing the 992-page book took much longer than she thought.

“I always wonder about that,” Streisand said. “Like, great authors, if it takes them a long time, how do they make a living?”

Confidence might have played a part in writing the expansive memoir. She said that she has doubted herself in the past, but “then there’s the part that knows from your soul, from my DNA, from my father, maybe even my mother, that tells you ‘You can do it.’ I don’t know how to describe it. It doesn’t come in a bottle.”

Streisand told Chris Willman of Variety that the audiobook version of her memoir—which clocks in at 48 hours—is slightly different from the print version. “Because I could change the language, it’s not exactly like the book,” she said. “It’s pretty much like the book, but then I would go off here and there and tell stories.”

Recording the audiobook, Streisand said, was something of a marathon.

“It took me six weeks, I think, to do the audiobook,” she said. “I was so sick of myself—can you imagine? I mean, you write a book for 10 years, then you’ve gotta say it out loud…”

Michael Schaub is a contributing writer.