Friends vet Marlo Thomas and her former talk show host husband Phil Donahue

Marlo Thomas and media pioneer Phil Donahue have been wed for 40 years.

And in the April/May issue of AARP The Magazine they share what has kept them strong all these decades as they promote their new book What Makes A Marriage Last.

The couple also collected stories from 40 celebrity couples such as Joanna and Chip Gaines as well as Michael J. Fox and Tracy Pollan.

New project: Marlo Thomas and media pioneer Phil Donahue have been wed for 40 years. And in the April/May issue of AARP The Magazine they share what has kept them strong all these decades as they promote their new book What Makes A Marriage Last

So in love for 40 years: The couple seen in 1981, the year after they got married

So in love for 40 years: The couple seen in 1981, the year after they got married

After receiving the shocking news of a close friend’s divorce, Thomas and Donahue started asking themselves what made them work.

They were trying to find a ‘secret sauce’ to a successful marriage. 

Thomas said, ‘When we marry, we promise love and devotion, but no wedding vow can prepare us for the unexpected.’

She was a role model for many: Seen on her popular TV series That Girl in 1966

She was a role model for many: Seen on her popular TV series That Girl in 1966

Her hit series in the 90s: She played Jennifer Aniston's mother on the show Friends

Her hit series in the 90s: She played Jennifer Aniston’s mother on the show Friends

The That Girl actress added, ‘We started to wonder if there really is a secret sauce to a successful marriage. 

‘And that’s when we decided to break an ironclad rule of our marriage – for the first time, ever – and decided to work on a project together,’ she said.

Thomas added they are their best when they support each other: ‘We often forget we’re at our best when we’re holding the hand – and having the back – of someone we care about.’

What is it? After receiving the shocking news of a close friend's divorce, Thomas and Donahue started asking themselves what made them work. They were trying to find a 'secret sauce' to a successful marriage; seen in May 2019

What is it? After receiving the shocking news of a close friend’s divorce, Thomas and Donahue started asking themselves what made them work. They were trying to find a ‘secret sauce’ to a successful marriage; seen in May 2019

Marlo came to fame in the 1960s with her sitcom That Girl.

Thirty years later she hit TV pay dirt again by playing the mom of Jennifer Aniston’s character Rachel Green.

Phil was the top talk show host of his era; The Phil Donahue Show ran from 1967 until 1995 and was a precursor to The Oprah Winfrey Show.

Over the span of nine months, the couple traveled cross-country to interview dozens of famous couples with 15-plus years of marriage under their belt and document their success stories.

The stories went into their upcoming book What Makes A Marriage Last that they cowrote.   

Fox and Pollan have had to work through his Parkinson’s Disease. 

Acting vet: And Fox and Pollan have had to work through his Parkinson's Disease. Pollan said: 'In marriage, you have to take it all – the good with the bad. If you love somebody, you deal with whatever it is they're dealing with. Their issues become your issues.' Seen in 2017

Acting vet: And Fox and Pollan have had to work through his Parkinson’s Disease. Pollan said: ‘In marriage, you have to take it all – the good with the bad. If you love somebody, you deal with whatever it is they’re dealing with. Their issues become your issues.’ Seen in 2017

But she has had a great attitude about it.

Pollan said: ‘In marriage, you have to take it all – the good with the bad. 

‘If you love somebody, you deal with whatever it is they’re dealing with. Their issues become your issues.’ 

They are friends: The couple asked Joanna and Chip Gaines what makes them tick. Chip said when you find the one, 'Pursue the person you love like a hornet'

They are friends: The couple asked Joanna and Chip Gaines what makes them tick. Chip said when you find the one, ‘Pursue the person you love like a hornet’

Joanna’s husband Chip said when you find the one, ‘Pursue the person you love like a hornet.’

Kevin Bacon, who is married to Kyra Sedgwick, added, ‘Whenever people ask us how we’ve stayed married, I’ve started staying, “Keep the fights clean and the sex dirty.”

‘I felt like that would just end the conversation.’

Viola Davis, who is married to Julius Tennon, said ‘My big thing about marriage – and it’s advice I give to all of my friends – is that it doesn’t start when you walk down the aisle. 

‘Your marriage starts when you look over at a person whom you love more than anything and there’s that one character trait that makes you say to yourself, Oh, man, that’s going to drive me crazy. And then the next minute you say, But you know what? I love him. That’s when your marriage starts.’  

John Leguizamo, who is married to Justine Maurer, added: ‘Don’t chase what you think will bring you happiness. Focus on the important moments.’ 

Writers: Over the span of nine months, they traveled cross-country to interview dozens of famous couples with 15-plus years of marriage under their belt and document their success stories. The stories went into their upcoming book What Makes A Marriage Last that they cowrote. Seen on March 4 in NYC

Writers: Over the span of nine months, they traveled cross-country to interview dozens of famous couples with 15-plus years of marriage under their belt and document their success stories. The stories went into their upcoming book What Makes A Marriage Last that they cowrote. Seen on March 4 in NYC