At 71, Olivia Newton-John has won four Grammys, sold 100 million records worldwide and has starred in iconic films.
But Newton-John began her career as a teenager. So looking back, what advice would she give her 20-year-old self?
"Don't worry so much!" she tells CNBC Make It.
"Gosh, there's so much I'd tell her. I wouldn't know where to start, to be honest," she says.
Before she was 18, Newton-John got her start singing on Australian radio and television shows and appearing in nightclubs across Europe. In 1973, at age 25, she hit American music charts with her first hit single "Let Me Be There" and she won two Grammys for her 1974 song, "I Honestly Love You."
Then Newton-John was catapulted into international fame at 30 thanks to her role as Sandy in the 1978 movie "Grease." The film produced No. 1 singles like "You're the One That I Want" and "Hopelessly Devoted to You." In 1981, she released her most successful studio album called "Physical," which hit double platinum.
But Newton-John says she would tell her younger self to "stick with her instincts," because they served her well. "I always went with my instincts," she tells CNBC Make It.
"I wouldn't want to undo anything I've done," says Newton-John. "Everything that may not have appeared to be good for me outside was a learning experience for me to be who I am now. So, I wouldn't not want to have experienced the difficulties, because they're part of your growth."
Newton-John, who was diagnosed with breast cancer for a third time this year after first being diagnosed in 1992, has been looking back on her career — she is auctioning off hundreds of items, from her "Grease," "You're the One that I Want" duet finale outfit (which went for over $400,000) to a little black dress she wore on her Physical Tour in 1982.
A portion of the proceeds from the Julien's Auction event will go to the Olivia Newton-John Cancer & Wellness Research Centre in Melbourne, Australia.
"I kept thinking that it would be a wonderful idea to auction off my ["Grease"] jacket and pants to raise money for my center," Newton-John told CNBC Make It. "Somebody had mentioned that they'd raise a lot of money. I thought, 'well, I have them for goodness sake, that would be a great idea.'"
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Correction: This story has been corrected to reflect that Newton-John was 25 in 1973.