Cardio is king when it comes to workouts. Trainers know it, doctors know it and Cameron Diaz knows it.

When the health-conscious actress and author stopped by OWN's offices in LA to talk about her research-oriented The Longevity Book, she zeroed in on the importance of cardio and its effect on not just the heart, but the entire body. "It's the best thing you can do," Diaz says.

The key to determining if you're getting the most out of your cardio workout , she explains, can often be measured in one tangible currency: sweat.

"Some people can get on the cardio machine and go for two hours at the same pace -- it's the same sweat, just a nice little glisten," Diaz says. "You want to be a fire hydrant in New York City that just got busted open, and you're pouring out after and everybody gets wet! That's the kind of cardio you want to do."

To work up that kind of sweat, you might expect to spend a ton of time on the treadmill. Not so, according to Diaz. "That cardio only takes five minutes," she says.

Diaz believes so strongly in the power of these quick bursts of cardio that she incorporates it into her own workout routine.

"I just get on my elliptical and I do intervals," she explains. "You sprint... for a minute. A whole minute. Then, you stop for a minute; you just kind of [jog to] bring your heart rate down. Let it come down, then a minute later... [sprint] for another minute."

Diaz continues, "Do that five times. You are bursting with sweat."

Not only is this routine good for the heart, but Diaz points to a variety of physical benefits.

"You're burning more fat than if you stayed on it for an hour, because what you're doing is you're making your body use this energy super-quickly," she says. "It's a jet engine [compared to] a car. It's just firing up everything -- and you're using all your muscles."

Plus, Diaz adds, you're concentrating on your form and you're fully in the moment, focused on your body's movement.

"Across all these levels and all these layers, you're actually doing more for your body than if you're just staying in a rhythm," she says.

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