The only problem is, which 'self' should I be?
At the most basic level, all of us come up against the phenomenological self. That is to say, the person we experience as ourselves. The bundle of experiences, characteristics, and attributes - physical, mental, and spiritual - which are 'me'. This is not the same as the person other people encounter; by (provisional, and in need of later tweaking) definition, a 'self' can only be self-experienced. It is who I am to myself.
But then, I am also aware of another self, the sort of self I want to be, the aspirational self. Sometimes I am just aware that the self I experience does not match up with well the person I like to think I am. Sometimes, more painfully, somebody else describes me, and I realise that I am indeed 'like that', even though I feel that is 'not really me' - I am forced to own their description, even as I really want to disown it. So a gap opens up between 'who I am' and 'who I want to be' - except more often than not, I do not see it that way. Rather, I see 'who I am' and 'who I really am'. Perhaps this is a delusion, but it is an important one; I harbour the thought that 'I' am really other than - better than - the self I experience.
The gospel of the world is that I can be, and should be, my aspirational self. 'Sanctification' is about being more myself, more the person I like to think of myself as being. And when I hit a roadbump - when there is something in my phenomenological self which I don't seem to be able to adjust - I should adjust my aspirational self instead. The goal is to bring the two together, one way or another.
But then there is what I will call the Christological self. In Christ, my identity is not about my self-identity. My true self has already been identified in him. I don't see it now, because it is hidden. But that doesn't mean it isn't real. My self is determined, not by me, but by Jesus Christ, his life, death, and resurrection. Because here is someone - the only person - who really and truly knows me better than I know myself. As my creator, he knows the self I was made to be; as my redeemer, he knows the self I have been eternally determined to be.
So the true gospel says: be yourself. But not the self that is determined by the mere phenomena of your existence, or even by your dreams and aspirations, but by who Jesus has determined you to be. And these are not the same. Just because I see something in me doesn't mean it belongs to my truest self. Just because I dream something doesn't mean it is who I really am. I am who I am in him, and to be a disciple is to look to him and to walk like him. And so to be myself.