Terminator: Dark Fate marks a return to form for the long-running franchise -- including the return of Arnold Schwarzenegger as the eponymous combat robot and Linda Hamilton as the iconic hero Sarah Connor, and at 63, Hamilton hasn't lost a beat when it comes to being a badass action star.

On Sunday, Hamilton and Schwarzenegger sat down with ET's Lauren Zima, while promoting their hotly-anticipated action epic, and Hamilton opened up about how the rest of the Dark Fate cast -- especially the franchise newcomers Mackenzie Davis and Natalia Reyes -- looked to her to set the tone and the expectations.

"The ladies are fantastic. And I don't think I had anything to add to their performances, they stood alone, and they stood strong. They were so prepared," Hamilton reflected. "I watched Mackenzie work, we went to gun camp together in Texas, and I was actually like, 'Oh s**t, I am just never going to be able to, not even compete with that, but to even match that.'"

According to Hamilton, the project came together because of how strong the bond was between the cast and how they all complemented each other on screen.

"I think the fact that the three of us were so committed and really fierce women and very good actresses -- if one of us had been a weak link, it all would have tumbled down -- but we really elevated each other every day," Hamilton shared. "They elevated me as much as I elevated them, that's for sure."

Schwarzenegger, however, had nothing but effusive praise for Hamilton -- both as an actress and as a de facto role model and leader for her co-stars.

"The whole younger team that was on the set kind of looked at her and saw her performance and how well she was prepared and how well she did with the stunts and how many times she did it and never complained about it," Schwarzenegger marveled. "She raised the bar really high in 1991 with Judgment Day, and then now, even raised it higher."

"So they had no choice but to go and follow that and try to outdo her," he added. "Which was impossible to do. So she was a really great motivation on the set."

However when it came to outdoing her co-stars, it seems that Hamilton had the toughest job when she had to deliver her own take on the famous line, "I'll be back," which Schwarzenegger made iconic in the 1984 original, The Terminator.

"You can't say it without sounding like him," Hamilton recalled with a laugh. "It's at the end of a very intense action scene and it's weapons and it's triple digit heat, and you're just giving it everything and then every time I would finish with that line, I would look at [director] Tim [Miller] and he would go, 'Sounds like Arnold. Let's do it again.'"

"She did a great job," Schwarzenegger said. "I wasn't there when she did it, but I saw it in the movie, and I was amazed that someone could say it in a different way than the way I said it."

"Tim guided me through it," Hamilton reiterated. "Because it really was almost impossible to say it after three decades of hearing it in your head with his voice."

Terminator: Dark Fate -- which serves as a direct sequel to the 1991 action classic Terminator 2: Judgment Day, while essentially ignoring the continuity of any other sequels in the franchise -- also marks James Cameron's return to the franchise that he created and directed the first two films in.

This time around, Cameron served as a producer and creative consultant while Miller -- who previously directed Deadpool -- helmed the production.

However, after so many sequels and so many years, Hamilton admitted that she had her fair share of hesitations when it came to returning.

"It took a little work on their part to bring me back," Hamilton admitted to ET. "Because I just was not really sure that I had anything more to say. It's been 28 years, and I'm like, 'Are you putting me in a wheelchair or what?' Because it was just so far-fetched to come back all these years later."

"But after careful consideration, and a vague outline of the story, [I began] thinking, 'I've got 28 years to fill in with character and make these decisions and then bring them to the sound stage,'" Hamilton explained. "And I went for it."

For Schwarzenegger, the decision was "much simpler," and was largely based on the involvement of Cameron.

"Jim Cameron told me the story after a motorcycle ride and I immediately said to him, 'I'm in. This is fantastic,'" Schwarzenegger recalled. "Especially after he told me he wanted to bring back Linda Hamilton. I couldn't wait to work with her again."