"Rigor Tortoise" also known as "Mr. Sandy Pants," the tortoise mascot at American Medical Response, captures the attention recently of grandchildren, from left, Cory Delanoy, 9, Abby Delanoy, 5, Emma Green, 2, and Gavin Green, 4, along with their grandfather Jim Maddox, 53, who works for AMA in Concord, Calif. "We wanted to be younger grandparents, so we can be active in the children's lives," Maddox said.

WALNUT CREEK, Calif. — When Jim Maddox got the news that he was going to be a grandfather, he was bewildered. Maddox, then 43, sat down for hours and contemplated what the new family addition meant to his life.

"I'm going to be a grandpa," Maddox, a Concord, Calif., paramedic, recalls thinking. "I have a demanding job. My wife and I are in the middle of our lives."

Then, little Cory came into their lives. And the overwhelming love he feels for the boy, now 9, is something Maddox says he wouldn't give up for the world. In fact, for Maddox, who is now 53, and his wife, Rhonda, 51, being content as a young grandparent came easy. They were young when they had their own daughters. And some of Jim's favorite childhood moments, such as climbing the Oregon mountains in search of berries, were with his own fortysomething grandfather.

"We wanted to be younger grandparents, so we can be active in the children's' lives," says Jim, who is also grandpa to Abby, 5; Gavin, 4; and Emma, 2. "I'm still working and making money, so it gives us the ability to do all sorts of things. And, we still do the roller coasters with them."

The Maddoxes and other grandparents around or younger than 50 hear it all the time: "You're a grandparent? But you're so young!" That's a perk. But being a modern-day young grandparent is also a lifestyle feat. They have dynamic lives, often juggling careers and relationships with a very active role in the care and rearing of their grandchildren. "These grandparents are shifting the attitude of what it means to be over 50," Owens says. "They're more likely to be playing Nintendo Wii with their grandchildren than sitting in the corner knitting. They may be retired but they've taken on a new business. They travel. Or maybe they're taking care of their grandchildren full-time."

Rhonda Maddox retired from her job with a national cheerleading company to be a full-time baby-sitting grandma, but she still runs community youth cheer teams, and her granddaughter, Abby, is one of her pupils. You'd think a cheerleading fiftysomething wouldn't want to be called the "G" word during practice, but Rhonda loves it. "I wanted my grandkids to call me grandma because it was such an honor to be theirs," she says.

Giselle Vieto of Fremont, Calif., who is 48 with three grandchildren age 7 and younger, has the kids call her mamagita, a term of endearment in Spanish from her native Costa Rica. Two years ago, she and her husband George knocked down a wall in their five bedroom home to make room for their daughter Janice, son-in-law, Andrew, and the couple's son, Freddy, who is 2. The Vietos' twentysomething sons, Joey and Gino, also live with them.

"The economy is so difficult right now that if they want to save for their future, this was the best way to go," says Giselle, who works full-time as the program director for Fremont Healthy Start.

In some ways, it's like being a mom again. Giselle realized that at a recent barbecue when she was the only one with a toddler in tow.

"When your youngest child is 20, you forget what kind of faces little kids make for certain foods. Those nostalgic memories are awakened."