Sylvester Stallone Opens Up About Son's Death, Discusses New Movie With Action Hero Co-Stars

Legendary Hollywood tough guy Sylvester Stallone has been traveling with co-stars to promote a new action movie, but beneath all the hype and glamour, he's a father still grieving the death of his son, Sage.

Sage Stallone, 36, died last month at his Los Angeles home. The cause of death has yet to be determined.

"It's tough. It's very tough … it's a horrible situation," Stallone, 66, told ABC News' Cecilia Vega.

After his son's death, Stallone cancelled all promotional appearances for the movie. His interview with "Good Morning America" was his first since then.

Support from good friends and family has helped him deal with the loss.

"Time, hopefully, will heal, and you try to get through it, but it's just something. It's a reality of life," he said. "I think it's important to get back and start reliving your life. Otherwise, you can go into a spiral."

So Stallone is back at work, surrounded by co-stars Jean-Claude Van Damme, former California Gov. Arnold Schwarzenegger, Jason Statham and Dolph Lundgren, to promote their movie, "The Expendables 2," which opens Friday.

They spoke to ABC News before the film's London premiere.

The film - which also features stars Chuck Norris, Jet Li, Bruce Willis and Liam Hemsworth - is a sequel to the 2010 hit. Its shoot-'em-up, knock-'em-out, high-flying plot focuses on a group of mercenaries who seek revenge for the murder of a friend.

Van Damme admits to being in awe of his castmates.

"I saw Mr. Stallone and Mr. Schwarzenegger when I was a kid in Belgium. They were like role models. They gave me inspiration to be what I am today," he said.

The cast of famous action heroes jumped at the chance to star in the sequel to "The Expendables," which brought in nearly $300 million at the box office.

Stallone, who co-wrote the film, said when he called the rest of the stars to invite them to participate, they were all enthusiastic.

Lundgren didn't need to be persuaded much, and Schwarzenegger was happy to be back in the limelight for his acting.

He had most recently made headlines for having fathered a child with his housekeeper while he was married to Maria Shriver.

"It was great to be back because the spotlight was not on me," Schwarzenegger said. "I was very appreciative that Sly was interested in having me in the movie."

They joked about helping Schwarzenegger get back into the swing of things.

"They thought that being eight years out of the game, that I maybe would not know how to hold a gun anymore," Schwarzenegger said. "Stallone was coming over, saying, 'Here's how you hold it.'"

"He was aiming at himself," Stallone said.

The cast primarily comprises vintage action heroes, but there's no retirement on the horizon for them. Van Damme is 51, Willis is 54, Lundgren is 57, Schwarzenegger is 65, Stallone is 66, and Norris is 72. At 44, Statham is the baby action hero of the bunch.

They might tease him about it, and might have laughed and joked on set, but they mean business.

Asked whether there will be a third "Expendables" film, Stallone said, "It's so rare to get the old team together. It's like having a great team and when that combo works, it's so rare and you just don't want to let it go."