"I think it's important, as an actor, to retain a sense of normalcy, because I've seen so many times people who have gotten a big head from a certain amount of success," Leo says. "I've seen it, I'm sure as you have, affect careers in a dramatic way. … At a young age, if you start to hear enough great things about yourself, you truly get a false sense of your own importance. And you start to feel like you're actually changing the course of history when, meanwhile, we're just entertainers for hire. We're making movies or doing songs or whatever. But not only that, I just don't want to be that type of person for my friends and family to be around. It would just be obnoxious."