"Taking on childhood obesity is really exciting," the personal trainer and new mom tells PEOPLE

By Michele Stueven
Updated January 09, 2013 06:00 PM
Trae Patton/NBC

Jillian Michaels is back with a vengeance!

The personal trainer, 38, is eager for people to watch her return to reality TV on The Biggest Loser‘s 14th season on NBC, focusing her attention on the show’s overweight youth.

“There were a lot of reasons for why I decided to come back,” Michaels told PEOPLE on Wednesday in Pasadena, Calif., during the Television Critics Association’s winter tour, naming fellow trainer Bob Harper as part of her motivation.

“Taking on childhood obesity is really exciting because both of us do work individually. Bob works with the First Lady [and] I work with the Clinton Foundation to help make a difference.”

Michaels – who left the hit show after its 11th season to focus on raising a family with her partner Heidi Rhoades – calls the series “a fan favorite,” adding, “It’s something I had greatly underestimated.”

Explains the fitness expert, “A vehicle like The Biggest Loser, with that kind of exposure and those kind of resources behind you, allows you to really get a message out and make a dent … I never hear the end of, ‘Go back to The Biggest Loser.’ “