I was recently reading about someone who had lost themselves in trying to be what someone else wanted. Obscuring their self, they failed in the relationship and failed in loving who they really were. I don't think in that specific case that if they had not hidden who they really were it would have changed the outcome, but it made me think, because it happens so often.
Being yourself does not mean being a collection of your flaws. That sort of definition would define a floor by the dirt on it. But being yourself does mean expressing what you really are and not something else. The the extent that you work on yourself, it means improving rather than changing yourself.
A long time ago, being yourself was considered a core part of having integrity. It was a significant part of the trope "to thine own self be true" and it meant avoiding pride and pretensions.
Now, being yourself seems to be used either as an excuse for annoying problems (e.g. "I'm a motor mouth and I don't show courtesy or respect to anyone else, but that is just the way I am") or a call to "free yourself" from trying to be someone you are not.
The later sense, that of freedom to be (rather than freedom to annoy) is important. We have gone from people who are being pretentious from an excess of pride to people who are submerging themselves because they do not love themselves the way that God does. I find myself wanting to tell people "You should allow yourself to be the person that God loves, not someone else." Nurture the person God loves.
Be that self. Then what love you give and receive will be true. But be there for God to love as he loves you and not something else. That is what being is all about.