As an actor, you're always at the service of somebody else's vision. In a play, it's more of the director's vision, and he or she's got their hands on you all the way up to opening night, and if it's a film, there are even more people.
Seek out that particular mental attribute which makes you feel most deeply and vitally alive, along with which comes the inner voice which says, 'This is the real me,' and when you have found that attitude, follow it.
Pain seems to be easier, or melancholy seems to be easier to portray in a character. I don't know if that's because I'm a human being or because I'm an Irishman or both.