Gerard Butler might not have played King Leonidas in Zack Snyder’s 300 had he not met this one condition.

More than 15 years ago, Zack Snyder made a film based on Frank Miller’s comic book, in which King Leonidas, along with 300 Spartan warriors, faced Xerxes and a huge Persian army at the Battle of Thermopylae. The production was a huge success, and Gerard Butler, playing the lead role, was recognized for his portrayal of King Leonidas.

But there was one person who was initially unconvinced about casting Butler in the role. That person was one of Warner Bros. studio’s top executives, Alan Horn, who, as he revealed during an interview with The Hollywood Reporter, couldn’t picture the actor as King Leonidas, because to him he had been the hero of Phantom of the Opera all along. However, he decided to give him a chance when he met him and saw him, but he had one condition.

Butler had done The Phantom of the Opera for us. I said, “I don’t see him for the role.” To me, he was the Phantom. A few days later, I get a call from this Gerard Butler. He says, “Can I come and see ya?” Scottish. So he comes to see me, and he’s really physically imposing.

I knew from Phantom that he smoked, and I thought I smelled it on him. So I said, “OK, you can have the part on one condition: You have got to stop smoking.” He said, “Are you serious?” I said: “Yes. Give me your word, and it’s yours.” And he said, “I give you my word.” I feel these guys and ladies are role models. And I believe the jury is in on smoking. No question — forget it. It’s bad.

Quitting smoking wasn’t a simple task for Butler. As he admitted, it took him 40 attempts, during which he sought various help – even from a hypnotist. But it worked, and for four years he didn’t smoke, until he met Russel Crowe, where, surrounded by smokers, he succumbed and went back to smoking for a month.

But as you can see, Butler cared a lot about his role in 300, since for it he took the trouble to quit smoking. And it isn’t surprising at all, even more so after we already know how much he gained from playing King Leonidas.