I like Andrew Soloman's words:
One would like to demarcate clearly the boundaries of the self. In fact, no essential self lies pure as a vein of gold under the chaos of experience and chemistry. The human organism is a sequence of selves that succumb to or choose one another. We are each the sum of certain choices and circumstances; the self exists in the narrow space where the world and our choices come together. ... We can never escape from choice itself. One's self lies in the choosing, every choice, every day.