That's the real issue though, of identity. When he speaks of changing who you are, he's talking about identity. On a deeply subconscious level, our essential being is undefined. In order to define itself, it creates the concept of identity. Our sense of self then becomes confused and conflated with identity. Identity takes on many apparent manifestations, from career to religion to politics to gender to race to sports team to favorite hobbies. The interplay between all of these different aspects form identity, their relationships are complex, prioritized differently among different people based on their subjective experiences. There are two great mistakes that occur. The first is the initial conflation between sense of self and identity. And the second is regarding identity as an ends, an ultimate definition of self, rather than a means. When these are a means, they can help one to understand the true value that each person has intrinsic to themselves by default. Everyone is valuable, important, and meaningful regardless of anything. But when we fail to see that, then these forms of identity become an ends; unless we achieve them, manifest them within the parameters of their definition, we cannot be valuable. They are then sought out to validate ones existence. People then feel that in order to be have a sense of value they must be the best at their career, or they must make the most amount of money, or have the prettiest spouse, or appear the most religious, or be the most patriotic. All of these are based on primitive impulses that drive us towards survival within the social group. Whatever is most closely associated with survival we place the great amount of value, meaning, and purpose on. But survival implies threats, and the perception of threats implies insecurity. Therefore, when people are in a state of insecurity they seek out external forms of validation. But when we are in a true state of security we are content; we don't feel the need to prove or validate ourselves because we already understand our true value and meaning. Socrates said that the highest form of understanding is experience, and when you experience that then you are truly alive.