I have a photograph at home of Fred Astaire from the knees down with his feet crossed. It's kind of inspiring because it reminds me his feet were bleeding at the end of rehearsals. Yet when you watch him, all you see is freedom. It's a reminder of what the job is about in general, not just being in musicals.
You can act truthfully or you can lie. You can reveal things about yourself or you can hide. Therefore, the audience recognizes something about themselves or they don't -- You hope they don't leave the theatre thinking that was nice...now where's the cab?'
I approach every part I'm asked to do and decide to do from exactly the same angle: who is this person, what does he want, how does he attempt to get it, and what happens to him when he doesn't get it, or if he does?