Consciousness

What does it mean to be self-conscious? or preferably have "self-awareness"?
It sounds a bit religious or spiritual to a certain degree, we usually hear it from zen masters and the Buddhist in their pursuit of enlightenment. Somehow it is the path to enlightenment; the ultimate virtue to be attained on one's way to unity.
I have found self-awareness such a valuable practice in daily life, when I put it in a question form:
why am I doing what I am doing?
why I need love or caring?
why am I offended?
why does it matter anyway?
why am I defining myself?
the last question is the killing one, give me a single rational reason for the time and energy we put into defining ourselves for others. We give them detailed description of what we did, do and will do, along with how, when and where. Then our reasons behind it with full description of what we think and why we think like that. But why we do this?

For me, we always follow the prime rule of nature: "whatever we do or we are tempted to do has a biological survival reason behind it".  With regard to self definition, I wonder maybe this automatic behavior is due to a need created by brain to communicate as brain cells sustain their liveliness by activities such as talking, communicating, and engagement in intellectually demanding activities. It is the optimum way to keep brain engaged without heavily loading it. Another analogy could be our lack of trust in others, in getting to know ourselves from their perspective. We want them to know us and see us from the angel we wish them to see, like those expert photographers that will make all the necessary settings on the camera and find the suitable angle and then ask you to just press the shoot button! voila, this is how I wish you to see me...
The natural need to talk and share ideas is one thing and the need to continuously define oneself is another. If this need is practiced without enough consideration, it can become a destructive habit! People will feel that you are talking too much about yourself, you are telling them how to think and feel about you and yet they do not see the image you wish them to see, and they start to distance themselves from you and become less interested to interact with you and this is the point you define yourself even more...