There's a lot of good advice in this long thread, but something in one of Jim Carroll's posts struck me as particularly to the point, in a way encapsulating of a lot of the different things said in greater detail by many contributors -

"All singing is, or should be a balance between technique, involvement and interpretation"

I hope Jim will forgive my comments on this.
Technique - training and use of the relevant physical instrument
Involvement - participation of the emotional faculty - 'feel'
Interpretation - deliberate shaping of the performance in line with your understanding

The above are referred to elsewhere, in a different order, as "the disciplines of the hands, the head and the heart". Seems to me that's all we have to work with, and if we are fortunate to get the balance "right" on occasion, then perhaps something more can happen.