Three days a week, Lillian Lucas pulls on a pair of black track pants, laces up her sneakers and hits the gym, where she teaches an hour-long Pilates class. Fifteen to 20 loyal students regularly show up to have Lucas lead them through a challenging series of planks, push-ups, abdominal exercises, stretching and more.

None of this seems all that unusual until you learn that Lucas is 90 years old. If Jack LaLanne had a partner in crime, it would be Lucas. The longtime Michigan resident has been teaching Pilates at the New Baltimore Recreation Department since 1978. But she wasn't always such a gym junkie. "My brother and sister died at 35 and 51 from heart trouble; my mother passed away at 47," she said. "So in my late 30s, I decided I'd better start exercising and see if I could live a little longer than they did." After sampling a variety of workouts, including jogging and walking, Pilates stuck.

Lucas' husband, Chester, passed away 11 years ago after 59 years of marriage. Shortly thereafter, Lucas suffered a stroke and other cardiac problems. "I decided it was even more important to hang in there."

As a result of her dedicated workouts, this mother of five, grandmother of 10 and great-grandmother of seven, boasts a healthy 140-over-80 blood pressure, stellar mental clarity and the type of endurance not often seen in women 20 years younger. "I see so many around me using walkers; they don't have the endurance I have," she said. "When you exercise, you stay sharp in mind as well as body. My doctor is very proud of me."

When she's not at the gym, Lucas enjoys cheering on her Detroit Tigers, Lions and Red Wings. She walks every day and sticks to a low-fat diet with plenty of fruits and vegetables and just the occasional sip of wine.

"There's nothing traditional about her," said daughter-in-law Florine Lucas. "She's just an energetic go-getter. My daughter, who is 32, took her class. She came home and said, 'Wow, Mom -- you should see Nana go!'"