"Be yourself!" is a bit of a catch cry that resounds deeply within us as human beings. I believe the reason why lies in our deep desire to see ourselves as valuable. It is a natural, intrinsic desire. And I believe that "being yourself" is a good perspective to have in many situations. For example, as a public speaker I understand the value of not trying to be someone else on stage. Nothing destroys rapport quicker than being fake.
Yet I don't think I've heard many people talk about the shadow side of "being yourself". You see, while we desire people to love us for who we are, without needing to be changed in order to receive acceptance, I think most of us also know that we are not YET the finished product. So who are we trying to be true to? Our current, unfinished self? Or our future, complete self that will not be happening till our time on earth is done (Rom 8:18-30)?
Most people I find are referring to "being themselves" as some sort of feeling-based state, where they are FEELING comfortable with the decisions they are making, or the stance they are taking, etc. But really when you search the Bible, often the characters found in the Biblical accounts are having to make decisions based what God is saying, not how they FEEL! Think about Moses at the burning bush. The call of God on his life required him to step out of a space he was extremely comfortable with. So was Gideon. And so was Jonah, who I got to speak about on Sunday (Podcast is available under 29th Jan, 2017).
Basically, my encouragement is to know what you're trying to be TRUE to. And from there my encouragement is to be true to what God is saying, and not what you're feeling. They are not the same thing necessarily!
Remember Proverbs 14:8 - "The wisdom of the prudent is to discern his way, but the folly of fools is deceiving."