Jane Fonda has had many personas over the last few decades - Keep Fit Jane, Sex Kitten Jane, to name two.

The award-winning actress has lived a thousand lives off the screen - she has been a producer, a political activist, a philanthropist, an exercise guru, an author and a trophy wife.

Famous for reinventing herself every few years, Fonda, now 73, has come up with a new book offering, Prime Time.

Part autobiographical - there's more about her distant father, her suicidal mother, her three divorces - and part self-help, it discusses how to love and live life in the final third act.

She dispenses advice on nutrition, exercise, health and friendship and gives the "lowdown on getting it up" in the twilight years.

She takes on the awkward topic head on - offering advice to those in their 60s, 70s and beyond who are still sexually active, or who would like to be.

Some of the advice is rudimentary: Her 11 "ingredients" for successful ageing include basic tidbits like not abusing alcohol, getting enough sleep, eating a healthy diet and remaining physically active.

Some will raise eyebrows.

Dispensing a tip from the book, she told Britain's The Telegraph: "A woman could be upset about a man liking to watch porn films.

"But it's important for the woman to know why. It's not that he doesn't love you or that you don't turn him on. It's more that men, as they get older, do need more stimulation. Men are way more visual than women."

Is she talking from experience?

"Sure. I have found from my own experience that instead of fighting him, you should join him. You go and choose the porn film. They make some that are more appealing to women now. That means you're halfway home."

What about talking dirty?

"I've done it all."

She also admits to using testosterone for the past three years. It makes a huge difference to one's libido, she said.

Her advice? Use it.

But it can be hard to enjoy sex when you are in your 70s or 80s - the body may not be as limber as it once was.

Her advice: "(Take) an anti-inflammatory...20 minutes before sex so you won't feel the aches and pains."

Fonda interviewed gerontologists, sexologists, urologists, biologists, psychologists and sexually-active older friends for the book, reported the Irish Independent.

She writes: "Don't think for a minute that older folks aren't getting it on. Use it or lose it." She should know.

"I was celibate for seven years after my marriage to (media tycoon and CNN founder) Ted Turner and thought that was the end of it. I was wrong."

The cover of Prime Time is an age-defying photo of Fonda, who looks whippet thin, perhaps due to a combination of healthy eating and plastic surgery.

She writes: "Yes, at 72 I had plastic surgery on my jaw line and under my eyes. I don't think I look like someone else, but my face is less droopy, and that makes me feel better."

The remarkably fit star, who has already written one best-selling memoir, My Life so Far, also gives an insight into her personal life.

She raves about her current relationship with music producer Richard Perry, 69, a man "who is not afraid of intimacy".

She said her life with Perry is one of the reasons she has felt happier as she has grown older. "I've fallen in love a lot," she told The Telegraph. "I've fallen in love all my life. What I did discover in the years after Ted and I split up is that I don't really have to be with a man.

"I always thought that if I weren't with a man I would fall through a dark hole and never surface again. I thought I needed a man to define me and that's not true any more. I'm in a relationship I wouldn't have had before.

"I'm not here to be validated. I'm here to have a companion. And I'm able to bring my full self to the table. Relationships at an older age can be far deeper and richer."

Her thesis seems to be that if you have things such as love and health when you reach your 70s, you will be happy.

Why did she become a sex therapist in the latest book?

Fonda told The Telegraph: "I don't pretend to be a sex therapist. I interviewed numerous sex therapists for the book. I don't pretend to be an expert. I'm not a gerontologist. I'm not a cognitive scientist.

"I spent four years doing a humongous amount of research because I wanted to know, am I the only person who is 73 and feeling better than she did when she was 23? Am I unique? And if I'm not, how come no one is talking about it?

"And I found I wasn't and I thought it was time we all started talking about it so that people weren't so afraid about getting older. Once you put aside oldness, it is not that scary."

She said she has always been drawn to men who could teach her something she didn't know - the alpha men who are leaders in their fields.

She said: "They were interesting men and I don't regret a moment I spent with them. My current boyfriend knows a great deal about music. And I sit on his studio floor and watch him producing."

Even in her sunset sunset years, Fonda has shown that there are hardly anybody quite like her. Her zest for life is not just amazing, it seems infectious.

This article was first published in The New Paper.