“Finish,” Greenfield, 36, tells PEOPLE, is his only goal for the race on Sept. 18. “I go for long runs and if I don’t feel like I’m going to die, I figure I can make it through the race.”
Greenfield first took part in the Malibu Triathlon in 2012, which was also his triathlon debut.
“The first, as you can imagine, was a little daunting,” he says.
The “avid CrossFitter” says he ups his endurance training before the race, which involves a half-mile swim, an 18-mile bike ride and a 4-mile run.
“The swim is always the most fun,” Greenfield says. “It’s also the first leg, so you’re not tired yet.”
Though he has low expectations for his finish time, Greenfield is thrilled to be involved.
“It is an incredible event and it raises money for Children’s Hospital Los Angeles for pediatric cancer research,” the dad of two says. “Every dollar is necessary and goes to good use. As a parent, I can’t think of anything more important.”
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And while Greenfield is a happy participant in the race, he doesn’t think his character, Schmidt, would join in.
“He would buy all the gear and then conveniently get hurt,” Greenfield predicts.