Robert Redford was convinced to star in 'Our Souls at Night' by Jane Fonda.

Robert Redford

Robert Redford

The 81-year-old icon was reluctant to appear in the film, having already starred in the Broadway production, but Jane's casting led Robert to reconsider his stance towards the romance movie.

Robert - who has frequently collaborated with Jane through the decades - explained: "Jane has this energy and she has this drive that forces things to happen, including taking a reluctant male character and pushing him into the spotlight.

"And that's what happened in the play and what happens in the film. So, that's why I like doing it again. It was fresh."

And Jane was similarly enthusiastic about being reunited with Robert.

She said, too, that having known each other for so long, it was easier to tease her more serious co-star.

Jane told 'Entertainment Tonight': "On 'Our Souls at Night', 50 years later ... when he wouldn't speak, I would just say, 'Bob, come on, you look like you're carrying the weight of the world on your shoulders. Lighten up, guy'.

"I just would rib him about it and I realised, oh, I've changed. I have more confidence and I don't think it's my fault."

Robert also explained how their lengthy friendship made the filming process much easier than usual.

He said: "It's one of those relationships that kind of fell into place without a lot of talk, without a lot of discussion.

"[It] went back to 1965. We worked together the first time and that was comfortable and easy. It's just been maintained all through the years, so it's been easy."