Kristen Bell Shape September 2010 cover bright pink bikini

Bell shows off her hard-earned body on the cover of Shape. Photo courtesy of Shape

Although Kristen Bell might be a self-described nerd, she's definitely a hot one at that.

The recently engaged actress flaunts her toned bikini bod on the September cover of Shape, wearing a bright pink two-piece with a ruffled neckline.

Then, readers get a bonus cover after turning the page, where Bell pops up again in a blazing red asymmetrical dress with a sexy cutout.

Inside the issue, Bell, a fitness junkie who's appeared on Shape's cover once before, shares 30 "stay-fit" tips, one for every day as the summer comes to a close.

Among various topics, the editors asked Bell -- who was walking on the treadmill during the interview -- about turning 30 this summer.

"I don't subscribe to the idea that aging is a bad thing," she says. "I'm extremely optimistic about what lies ahead of me. Look at Glenn Close, Helen Mirren, and Meryl Streep: They're the best at what they do, and beautiful too!"

As for plastic surgery, Bell says she wouldn't even change the tiniest thing like the freckle on the tip of her nose.

"If I really had the urge to change something, I'd just stop looking in the mirror," she says. "It's a lot cheaper to cover your mirrors than it is to change something about your face!"

To stay body beautiful herself, Bell likes to keep moving throughout the day, which includes hiking and taking the stairs whenever possible.

Bell is red hot on Shape's bonus cover. Photo courtesy of Shape

"If I can burn 10 calories by avoiding the elevator, I'm all for it," she says. "More flights of stairs means I can eat more candy!"

Diet-wise, she's into eating organic and has recently planted her own organic garden with veggies, fruits, and herbs.

"Maybe it's my biological clock, but I wanted to be part of the nurturing process," she says. "We all get to a point where we feel maternal, whether we have a kid or not!"

Speaking of family life, Bell and fiancé Dax Shepard are proud homebodies.

"I have to do these events for my job, and I enjoy them, but on a daily basis, I'd rather get up early and go to bed early," says Bell.

"Our idea of an exciting night is cooking dinner for friends and playing board and card games. It may sound nerdy, but it's fun!"

To read more of Bell's stay-fit tips for both her mind and body, head over to and pick up the issue on newsstands now!

In related news, read up on bikini babe Marisa Miller's fitness and diet tips.

And find out which foods will age you faster.