By peoplestaff225
Updated August 30, 2008 09:00 AM

Last month we told you about Jennifer Lopez‘s secrets for getting her pre-baby body back — she’s preparing for a triathlon! And as the date of her competition looms — she’ll be swimming, running and biking her way through Malibu on Sunday, September 14th — the singer/actress, 39, continues to train on a daily basis.

Jennifer’s trainer, Gunnar Peterson, tells that the star was most nervous about the swimming portion of the event — it’s something that doesn’t come naturally to her. At first, "she was swimming laps and touching the sides [of the pool]," he says. "Then we moved into open water. We did baby steps, buildingit up distance-wise and intensity-wise."

For more on Jennifer’s training regimen — and for other tips on how to feel and look like a star — click over to’s BodyWatch gallery!