"I like to do things and have fun," Christie Brinkley, 59, told Us Weekly at the event of keeping in shape. Credit: Jon Kopaloff/FilmMagic

Like fine wine, these supermodels get better with age!

Christie Brinkley, Kathy Ireland, Tyra Banks, and Heidi Klum showed off their toned bodies -- and spilled their secrets to staying fit -- at the 50th Anniversary of Sports Illustrated Swimsuit Issue party held in Hollywood on Tuesday, Jan. 14. 

"I like to do things and have fun," Brinkley, 59, told Us Weekly at the event of keeping in shape. In addition to riding her bike, skiing, and dancing, Brinkley also logs more traditional workouts. "I really go use the Total Fitness gym," she continued. "That's not just advertising."

All of that fun is paying off: The mother of three flaunted her long and lean legs in a sexy black mini dress with a plunging neckline.

Kathy Ireland, 50, glowed in a strapless green gown while sharing that she prefers to work out with Mother Nature. "I love being outdoors," Ireland, who appeared on 13 consecutive Sports Illustrated Swimsuit Issue covers, said. "My sense of adventure outweighs my grace."

Heidi Klum, 40, admitted that her kids help her to stay active -- but in a different way. "[Before having children,] I had more time to go to the gym," she said. "Now having kids, I am trying to integrate their activity into my life." That means bouncing on their giant trampoline, swimming in the pool, or taking their dogs for walks.

However Tyra Banks, 40, has been busy recovering from holiday indulgences. "I'm in the process now of really trying to work out," she told Us. Wearing a black, negligee-inspired dress dress that showed off her cleavage, Banks admitted that her holiday season was packed with delicious food: "I lost my mind but it was worth it. But I couldn't zip up my dress on New Year's Eve."

To shed the pounds, Banks said she is cycling. "I'm going to start Pilates and eating much healthier," she added.