Be Yourself. It is a concept that describes a very important aspect of mental health, but one that I think is ineffectively communicated through such a short phrase. We often tell this to children as a handy social guideline without realizing that adults are the only people who really have any strong concept of what defines "yourself."
I think a more appropriate guideline would be, "Don't do or say things that you think are wrong." That is a statement I think most kids would easily understand. "Be yourself" could mean all kinds of other things like:
- Don't censor yourself just to appease others
- Behave however you want to regardless of what others think
- Don't ever emulate anyone else's behaviour
- Only do things you are comfortable with
And the list could go on, but the point is that while some of these rules may be appealing, there are always times to break them. Social norms are what make society possible, and we all benefit from society whether we care to admit it or not (think cave man life or Mad Max). While I don't believe anyone should go around blindly following others, on the same token, learning from others is a practical and valid way of constructing an identity. If the goal is a sense of identity and self esteem, then reaching that goal has to do with self-evaluation and making reasoned choices more so than being unique at all costs. The fact that you got an idea from someone else shouldn't weigh in on your acceptance of it.
To get at the core of what defines a person, what really stands out is the way their mind works. How a person reacts to a situation is a more intrinsic quality then their values and memories which are dependent on experience. In this regard, not being yourself would be synonymous with over-analyzation of one's own actions to the point of mental anguish (otherwise known as trying too hard), and that is a definition I can stand behind.