Now that Jane Fonda is older and wiser, she's feeling better than ever. But that wasn't the case when she was younger. The activist and actress, now 85, had a not-so-great childhood. “Being young is really hard. Don't let anyone kid you,” Fonda told PEOPLE. “I wish when I was younger, someone had said to me, ‘Don't give up. Keep going. It'll get better.'”

When Fonda was younger, she never dreamed of being an actor. “Young me did not want to be an actor. I didn't think I had talent. I didn't think I was pretty enough. I had a lot of body dysmorphia,” she said. “I was pretty lost as a young person.”

After struggling with bulimia in the early 80s, Fonda took an exercise class with an instructor named Leni Cazden. This helped her eating disorder, and was also the start of her fitness empire. She released Jane Fonda's Workout, and was a huge sensation, selling over 17 million copies.

Fonda shared that the best part of it was the feedback she would hear from other women, telling her that her videos changed the way they viewed themselves. Even at 85 years old, Fonda is still active. She exercises regularly with a trainer and sticks to a solid, healthy diet.

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One of the reasons she's much happier than she ever was is because of her age. With time, all the questions her younger self asked had been answered, “Who am I? What am I supposed to do in life? All of that has been answered. I don't take anything for granted, and I'm just amazed that at my age I'm still working and have a lot of energy.”

See Jane Fonda in theaters May 12th in the comedy Book Club: The Next Chapter.