There is no reason I see to believe in the 'identity' of physical things—especially not at the level of a human being. We're conscious, and aware of that consciousness. We enjoy/suffer from a peristent delusion of 'self'. We know we're gonna die and we've evolved in such a way that we are programmed to fear and avoid it.

Our mortality + 'self' delusion + consciousness makes us say stuff like:

I want me (whatever that is) to continue living and doing stuff.