Christie Brinkley Says She Was Once Told She'd Be 'Chewed Up and Spit Out' of Modeling by Age 30 (Exclusive)

Christie Brinkley admits she's had many emotions about aging.

The model, 70, was once afraid to get older, because she was told that getting older meant aging out of the industry.

"They told me by the time you're 30, you'll be chewed up and spit out of this business," she tells PEOPLE exclusively while chatting about her new clothing collection with HSN. "But 50 isn't 50 anymore. Thirty isn't 30 anymore."

Brinkley, who turned 70 in February, says she's been having a great year and never dreamed that this is what her life would be like at this point.

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"It's the start of a great decade," she gushes. "I'm hearing from women on my Instagram, like, 'Now I'm looking forward to my 7-0. I was kind of dreading it, but you're making it look so fun. And it is really important to make it fun and so far so great."

Not only did Brinkley just launch her HSN collection — called TWRHLL — but she also starred on a legendary cover of Sports Illustrated Swimsuit this month as well, alongside several other past models of the magazine. She calls her most recent feature with Sports Illustrated a bit "crazy," in the best way. She also gushed over sitting next to Martha Stewart, 82, for the photo.

"I think it's really, really fantastic that Sports Illustrated not only has me, but Martha, who looks so great," she says. "She has the distinction of being the oldest cover model on Sports Illustrated. I sat right behind Martha and I can vouch that her skin is perfection!"

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Brinkley praises outlets like Sports Illustrated Swimsuit and even HSN for working with older models and older women, because she says age isn't what it used to be and women need to keep "getting out there and keep shining."

"There's so many women that are taking on new jobs that they always wanted to do, but they had that job before that they needed to do, and now they're doing passion projects," she tells PEOPLE. "That's really exciting. So many women are getting out there and changing the ideas of what these numbers represent. Women at 70 want to see women like me and that's okay!"