If you really do want to be an actor who can satisfy himself and his audience, you need to be vulnerable. You must reach the emotional and intellectual level of ability where you can go out stark naked, emotionally, in front of an audience.
For me and for I'm sure any actor, each role is a different challenge to prepare for in a different way.
The condition every art requires is, not so much freedom from restriction, as freedom from adulteration and from the intrusion of foreign matter.