LOS ANGELES — It’s hard to think of someone in public life who has had more disparate phases and identities than Jane Fonda.

There’s the brilliant actress (and daughter of a Hollywood legend), the polarizing political activist, the exercise maven, the rich celebrity wife, and now, once again, the working actress. Fonda admits that this last phase – what she calls her “third act” – has taken her by surprise.

“It’s much more than I ever expected,” she said. “There are a lot of firsts in my third act.”

Whatever the role, Fonda invests it with fierce determination and ambition, so it’s not surprising that the age-defying 76-year-old hit the ground running when she returned to acting, after a 15-year sabbatical, in the 2005 comedy hit “Monster-in-Law” and hasn’t looked back.

After wowing the red carpet with her stunning looks at the recent Cannes Film Festival as an ambassador for L’Oreal, she went to Switzerland to play an 80-year-old diva in “Youth,” for Paolo Sorrentino, who directed the Oscar-winning Italian film “The Great Beauty.” Earlier this year, Fonda made “Fathers and Daughters” with Russell Crowe (“He just knocked my socks off”) and will be seen this fall with Tina Fey and Jason Bateman in “This Is Where I Leave You.”

In August, she and her “9 to 5” costar Lily Tomlin begin filming the new Netflix series “Grace and Frankie,” and she’s returning for at least one episode in her role as the powerful owner of a cable news network in HBO’s “The Newsroom,” for which she received an Emmy nomination.

This month, Fonda received one of her hometown’s most prestigious honors – the American Film Institute’s Life Achievement Award – at the Dolby Theatre. She is only the eighth actress to receive the award. Her father, Henry Fonda, won it in 1978.

AFI President and Chief Executive Bob Gazzale said the honor is for “work that has stood the test of time…. One of the gifts of honoring somebody like Jane is the ability to go back and revisit the work. ‘They Shoot Horses, Don’t They?’ is the film that really hit me.”

An edited version of the show will air Tuesday on TNT and in August on TCM. Among those paying tribute were brother Peter Fonda, Michael Douglas, Meryl Streep, Catherine Keener, Sally Field and Penny Marshall.

Even after a lifetime of honors, Fonda is thrilled about the AFI salute. “If you had asked me three years ago if I thought this was in my future, I would say I can’t even hope for such a thing,” she said. In fact, she said she was so moved when she learned of the honor last fall, “I burst into tears.”

The award, she said, “is not for one film. It’s for a body of work. It’s very competitive and very important, serious longtime heavyweights in the industry make the decision about who gets it. It’s like a major stamp of approval and respect from your industry peers.”

Looking at the scope of Fonda’s far-flung career, Gazzale notes: “Hers is an epic adventure.”

Fonda thinks of her career as an endless process of reinvention. She admits with a laugh that when she sees her earliest films, such as 1960’s “Tall Story” and 1962’s “The Chapman Report,” “I think ‘Who is that person?’ I don’t recognize her. I really didn’t know what I was doing.”

Ironically, Fonda never really wanted to follow in her father’s footsteps. And if not for landmark acting teacher Lee Strasberg, she probably wouldn’t have.

It was Strasberg who told her she was talented. “I needed someone who was not a parent or an employee of a parent to say, which he did, ‘Wow, you have got something.’ My life changed. That was a big deal. That was when I committed myself.”

That commitment led to her becoming perhaps the leading American actress of her generation. She won Oscars for 1971’s “Klute” and 1978’s “Coming Home,” as well as nominations for 1969’s “They Shoot Horses, Don’t They?,” 1977’s “Julia,” 1979’s “The China Syndrome,” 1981’s “On Golden Pond” and 1986’s “The Morning After.”

But she wasn’t happy.

“I didn’t know who I was or where I was going,” said Fonda. “I’d really kind of gone off the track and I can’t act when I feel that way. So I left.”

She was divorced from second husband Tom Hayden in 1990 and moved to Atlanta in 1991 when she married media mogul Ted Turner.

“That was an important thing for me,” she said. “Ted taught me how to laugh. I come from a family that is very serious, so Ted was a very important part of my healing.”

So was writing her candid 2005 memoir “My Life So Far,” in which she talked about her three-decade struggle with bulimia, her failed marriages, her mother Frances’ suicide when the actress was just 12, her famous father who was often cold and distant, and her anti-Vietnam War activities that nearly derailed her career in 1972 when she was photographed in Hanoi on an antiaircraft gun – an action for which some still can’t forgive her today.

“Writing a memoir if you really go deep, it is extremely cathartic,” said Fonda. “It can help you understand where you are going. You can’t know where you are going if you don’t know where you have been. Writing my memoir showed me where I had been and things about myself and patterns. It gave me a lot of confidence, combined with the sort of lightness I got from Ted. It helped me to become almost like a new person. I was not the same person when I was 50.”

Fonda also is a popular presence on Twitter – she has over 600,000 followers – and reports she has had “tremendous feedback” from her website, janefonda.com, and her blog posts on subjects including a butternut squash recipe, her music producer boyfriend Richard Perry’s battle with Parkinson’s disease and the infamous “Hanoi Jane” photo that she “will regret to my dying day.”

The Hanoi Jane label surfaced again on the Internet last fall when it was announced Fonda was the AFI award recipient. Some veterans voiced their displeasure at her being named the commencement speaker at the UCLA School of Theater, Film and Television’s graduation this month.

“It makes me sad,” said Fonda. “They haven’t healed. I get letters from time to time from vets who say ‘I have suddenly realized you were right’ (about being antiwar). I made ‘Coming Home’ because of my three years of working with soldiers. It was all based on what I learned from soldiers.”

Meanwhile, the fitness pioneer has released more than 20 exercise videos since 1982, and her latest series of “Prime Time” DVDs is geared to baby boomers. She’s managed to write 25 chapters of her first novel.

Fonda knows she has defied the odds in a youth-obsessed Hollywood that is especially unkind to actresses over 40, let alone over 70. “I feel very blessed,” she said. “I did not think my third act would be as rich professionally, and as varied.”

While in her 40s, said Fonda, “I wrote a book called ‘Women Coming of Age,’ and in it I wanted to give a cultural face to older women. Little did I know I would end up living it in my 70s.”