Jennifer Lopez is going to "tri" her hand at athletics.

Perhaps inspired by Katie Holmes‘ New York City marathon run, the multi-hyphenate is training to participate in a triathlon this fall.

J.Lo, who turns 39 on July 24, is currently hard at work with longtime trainer Gunnar Peterson to prep for the grueling swimming, cycling and running endurance event, Gunnar tells OK!.

“The workouts change daily, depending on the day, the time and the freedom,” he says. “She’s going to get it done because she wants to.”

But don’t think the workout regime takes time away from her and Marc Anthony‘s new twins, Max and Emme, 5 months. Having juggled multiple careers and business ventures in her life, the actress has everything "in check," Gunnar says, and would never prioritize something else over her children.

"She may be the most efficient multitasker I know. She literally has every aspect of her life in check,” he says. “She doesn’t have a nanny, a chef or a nutritionist. She makes time for the kids. Family comes first.”

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