Joaquin Phoenix ''can't imagine'' a life without acting.

The 'Joker' star admits he isn't sure what he would be doing if he hadn't made it as an actor and feels ''super lucky'' that it's his job.

He said: ''It's hard for me not to get sentimental about acting, because this industry has provided me with so much. I can't imagine a life without it. Work is one of the most fulfilling things that I do. I don't know what I'd have done if I hadn't been successful. I got super lucky.''

And the 44-year-old actor admits he wasn't initially sure about taking on the role of the Joker.

He added: ''I've been struggling with making decisions for the last few years. I wasn't certain this was right for me, but I also wasn't certain that it was something I could pull off. It's important to know that I get along with the director because I've had a couple of situations where I didn't. That's very difficult to deal with.''

Phoenix had to shed a lot of weight for the role and admits is ''harder'' the older he gets.

Speaking to OK! magazine, he shared: ''Sure. It's harder but you do what is necessary for the character. The first time that I lost a lot of weight for a role, I really didn't know what I was doing. Now that the feeling of hunger is familiar, you dread it. I put on eight pounds before I started to lose weight. I figured I'd spend a month eating whatever I could and then start the diet, which was so stupid.''