Credit: Julien M. Hekimian/Getty Images

Jane Fonda isn't opposed to turning back the hands of time.

The Oscar-winning actress, 72, is opening up for the very first time about her decision to go under the knife.

"I recently had plastic surgery. It was a hard decision to make, and I decided if I'm going to do it, I'm going to tell the truth," Fonda tells Entertainment Tonight. "I'm writing a book about aging, so I can't write that book and not say I've had plastic surgery. And you know, I just decided it was for me -- I don't want to have bags under my eyes that make me look tired, and so forth and so on."

Fonda -- who launched a series of successful fitness videos in the '80s -- says she's always paid special attention to her appearance.

"I have, in my life, been obsessive about exercise, about most everything. But one of the good things that happens when you get older is everything comes into perspective," she says. "I have a new hip, I have a new knee, and I'm going to soon be be bionic. If I don't stay active my body stops functioning."

The actress -- who next stars in You Again opposite Kristen Bell and Jamie Lee Curtis on Sept. 24 -- is set to release two new workout DVDs this November.