Denise Austin, 66, is proving that age is just a number. 

The fitness guru took to Instagram on Friday to share a then-and-now picture of herself in a one-piece swimsuit she wore while filming "Getting Fit with Denise Austin" 30 years ago.

"Flashback Friday!!! WOW!! what an incredible memory to look back on!!" she began her caption.

The workout video legend sported a pink one-piece with a white trim border as she posed on the beach in both pictures.

DENISE AUSTIN, 66, FLAUNTS TONED ABS IN BIKINI TOP AND SHORTS

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"This Then and Now brings back such nostalgia…I wore this suit back in the ‘90s while shooting my TV show!! How many of you remember watching???" she asked her social media followers.

Her fitness television show was canceled in 2008.

"still feel as confident and fit as ever and love that I have this suit to remind me how far I’ve come!! Longevity baby!!! Thank you to everyone that has always supported me.. THEN and NOW!!!!xoxo," she concluded.

Denise Austin during the '80s

Denise Austin in 1985. (Getty Images)

Fans loved Austin's positivity and commended her in her comment section on Instagram.

"Wow you are so inspiring And very beautiful love your positive VIBES," one user wrote with another adding, "My mom and I worked out to your show multiple times a week. I have very fond memories!! Looking fab in your hot pink suit then and now."

Another user wrote, "I have been doing your tapes for 30 years. My daughter just got married and I was the same weight as when I got married." 

Denise Austin flexing

Denise Austin has been a fitness instructor for decades. (Photo by Tibrina Hobson/Getty Images)

During Austin's career, she recorded several fitness videos and wrote a few books on how to stay in shape, including "Pilates for Every Body."

Austin's daughter, Katie Austin, 29, is following in her mother's footsteps.

Denise Austin and Katie Austin on the runway

Katie Austin and Denise Austin walk the runway for Sports Illustrated Swimsuit Runway Show in 2022. (Getty Images)

Last summer, Austin walked in the 2022 Sports Illustrated Swimsuit Runway Show in Miami with Katie.

"For [SI] to even ask me at 65 years old to be in a bikini — I mean, it was a huge thrill and I just went for it," Austin told Fox News Digital last year. "What the heck?"

She said she hoped it would inspire women that it’s never too late to get back into shape. 

Denise Austin hugging her daughter

Katie Austin hugged her mom, Denise Austin, while walking the runway for Sports Illustrated Swimsuit Runway Show in Miami Beach, July 2022. (Getty Images)

"First, love the body you’re in," Austin said. 

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"Do the best that you can. I truly believe in having a good attitude. It truly comes from within. I love what I do, and I feel like I can help women out there feel better about themselves. Exercise, eating right, having a good attitude, a good night’s rest – all of it helps with that healthy lifestyle," she continued. 

Denise Austin SI Runway

Denise Austin walked the runway for Sports Illustrated Swimsuit in July 2022. (Photo by John Parra)

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"I want women to truly try their very best to eat healthily and to move more. That’s my message. I have always said that for all these 40 years, just do the best that you can. That is the key," Austin concluded.