Kevin Costner Reveals 'Horizon' Was the Most Challenging Project He's Ever Taken On: 'We Never Stopped Working'

Kevin Costner is no stranger to hard work.

At the premiere of his new film "Horizon: An American Saga" in Los Angeles on Monday, the 69-year-old actor discussed the time and effort that went into creating the project and expressed his pride in the movement.

"This is my town, a company town. I love what Hollywood can be and what it has been. It's an honor to be a part of the history of everyone else who's brought movies to Westwood, to the Chinese (Theatre). This is a ceremony, something we all go through. We get to celebrate. I'm proud of the film people will see tonight. When it's time to let it go, it will be in the river for people to watch long after I'm gone."

Costner elaborated on the challenges of his involvement.

"The completion time of 'Dances With Wolves' was 106 days, and 'Horizon' was arguably as big, but we finished it in 52 days. The only reason for this was due to the people who worked with me. We never stopped working until the project was complete."

Besides starring in the movie, Costner also directed "Horizon," which he co-wrote with John Baird. The cast includes Sienna Miller, Sam Worthington, Luke Wilson, Abbey Lee, Jena Malone, Giovanni Ribisi and others.

Fuhrman praised Costner's leadership skills, calling him an "incredible leader."

WATCH: KEVIN COSTNER SAYS ‘HORIZON’ WAS COMPLETED IN 52 DAYS

"I am deeply grateful for Kevin's visionary approach to filmmaking. I have admired him for many years and was thrilled when he asked me to be part of his latest project. Western films have always been a dream of mine, and I was excited to finally have a role in one. I appreciate how Kevin created a unique and interesting world for his characters, rather than relying on typical action scenes. It was a refreshing change from the usual gunfights and I felt like I was part of something special."

"This film is not just about the history of America, but rather the journey of many individuals who went out with the hope of achieving their dreams and faced various challenges. Telling this story on a personal level with each character was a significant challenge. Kevin's leadership and determination to be the best version of himself every day inspired me to rise to the occasion."

Isabelle Fuhrman, star of the TV show 'Horizon,' praises Kevin Costner as an 'incredible leader.'

""Kevin Costner is a hard-working, well-prepared filmmaker who is open to capturing unexpected moments and is a top-notch filmmaker," Wilson said."

In an interview with Planet Chronicle Digital, the Oscar-winning actor disclosed that his 15-year-old son, Hayes, is not the only Costner child to display their acting talent in the film.

"My seven children are all supportive of each other," Costner revealed. "In chapter two, my oldest son had a scene, and a small part again."

He quipped, "I simply aim to ensnare them."

WATCH: LUKE WILSON SAYS KEVIN COSTNER ‘LEADS BY EXAMPLE’

Costner's ex-wife Christine Baumgartner is the mother of their children Hayes, 15, Cayden, 17, and Grace, 14. The couple divorced in February after 18 years of marriage.

Additionally, he has three adult children - Annie, Lily, and Joe - with ex-wife Cindy Silva, and a 26-year-old son, Liam, with former partner Bridget Rooney.

Hayes, Costner's younger son, made his debut in the first film of the post-Civil War drama at the age of 13, while his older son appeared in the second part of "Horizon."

"I'm so happy that he has that now for the rest of his life," Costner said. "I haven't pushed my children into this, and this might be his only dabble in it, but he's memorable. And for me to have him, I'll never forget it."

Kevin Costner is proud of the film "Horizon."

Last week, Costner announced on social media that he wouldn't be returning to season five, part B of "Yellowstone" after months of speculation.

"I have some news to share with you all. After working on 'Horizon' for over a year and a half and considering 'Yellowstone,' which is a beloved series that we all love, I have come to the realization that I won't be able to continue with Season 5 or any future seasons," he announced on Instagram.

"The experience that transformed me was something I loved and I know you loved it too. I wanted to inform you that I won't be coming back. Despite the wonderful relationship we've built, I'll catch up with you at the cinema."

In 2025, Costner will release a new project on FOX Nation, following his previous hosting of "Yellowstone: One Fifty," which delves into the history of the national park.