Brooke Shields isn't letting her age define her.

The 55-year-old model believes her best years are still ahead of her and she owes her confidence to her teenage daughters, Rowan, 17, and Grier, 14.

Shields told People magazine that her new frame of mind came after her kids called her out. "I was wearing those big bathing suits that had as much fabric as possible," she admitted. "My daughters were like, 'Mom, it's ridiculous.' It was sort of seeing myself through their eyes and just celebrating things like my butt. Things I just would never want to focus on in my life. Being 55 and saying 'Wait a minute, women over 50 are not done.'"

The actress added, "If you're that age, especially if you are an actress, it's like 'you've had your career, relax,' but I think I'm just starting."

BROOKE SHIELDS, 55, PUTS TONED LEGS ON FULL DISPLAY IN SWIMSUIT PICS

Brooke Shields has been practicing body positivity.  (Photo by Jim Spellman/Getty Images)

Like many during the pandemic, Shields was forced to reevaluate her lifestyle and make adjustments to eating and working out since gyms were closed. 

"My Instagram workouts were never meant to be a stressor," she confessed. "They're just accessible, and a way to have movement and endorphins. It's funny to do arm presses with two bottles of wines. We don't all have our fancy gyms at the moment but I can guarantee, if you do something for five minutes, it will be a positive."

Shields says she "worked hard" over the summer "every day" stayed motivated and getting fit. 

BROOKE SHIELDS SAYS MAINTAINING HER TONED FIGURE IS A 'DAILY STRUGGLE' AMID CORONAVIRUS

"I was never skinny," she said. "I was always athletic which means you don't fit in the sample sizes. My daughters say I'm curvy. To them curvy is different. I watch them celebrate it. I'm learning from them and they always say you're better off with something that shows your body rather than a muumuu."

The former Calvin Klein model noted that she's also readjusted her attitude. Instead of self-deprecating jokes, she's been practicing body positivity and affirmations.

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"I don't want my girls to do that. Just think of how great it would be if we can all feel this larger than life energy," she said.