Richard Simmons, Katrina Bowden 'Sweat to the Oldies' in Old Navy activewear

Known for his big hair and even bigger smile, fitness personality Richard Simmons, 64, has been making people laugh while they sweat for decades.

Simmons brought his unstoppable energy to the Aerospace High Performance Center in Manhattan Thursday, where a group gathered to try out Active by Old Navy workout gear while taking his famous "Sweatin' to the Oldies" aerobics class.

While Simmons wore a custom-made Old Navy outfit embellished with crystals that he said was inspired by the Harlem Globetrotters, the ladies wore colorful pieces from Old Navy that were made with GoDRY moisture-wicking fabric to let skin breathe and compression technology to sculpt a flattering physique.

"I think when you're working out and you have fuschia and pink and peach and the color of passion--purple--and you feel good about what you're wearing, you're apt to have a better workout," Simmons told Newsday. "I'm kind of sick of the gray and the dark blue and black. Women who are 200 pounds come into my studio in black and say 'Does this make me look thinner?' I say 'No, but I'd rather you be in bright, happy colors.' "

"30 Rock" actress Katrina Bowden came to work out the well-toned body she flaunts on the cover of the current issue of Maxim in an Old Navy compression jacket (on sale for $30 at oldnavy.com) and color-block compression capris ($22.94 at oldnavy.com). 

Bowden said she does kick boxing, yoga and boot camp classes multiple times per week to stay in shape.

"I just discovered Old Navy [activewear] and I think it's really awesome," she said. "It's very affordable but it rivals the top workout clothes like Lululemon and Nike that we all love. The compression gear really holds you in so you feel sexy and slim."

While the Old Navy collection features leggings, tanks, shorts, jackets, hoodies, yoga pants and sports bras, Simmons warns not to forget about the right pair of sneakers.

"There are so many fun, funky shoes," he says. "When you're doing cardio you have to make sure you have padding on the toes, the heels and both sides of the foot--you need not a running shoe, but a shoe that works for aerobics."

The Old Navy gear was comfortable and airy as Simmons led his fast-paced cardio class to songs old and new, including two that he wrote himself.

"When you like what you're wearing and you feel like you look good, you'll probably be more motivated to work out to a more intense level," Bowden said before leading the class in the front row. "Then you'll look even better in your clothes--so it's a great cycle."

Active by Old Navy pieces on sale now start at less than $5 and are available at Old Navy stores and oldnavy.com.