As you know confidence is drug to all mental problems. Many people have lack of this drug or some have over doze of it. You must understand how to balance it. If you don't have confidence in your work then why many people will have confidence on your work? You should be confident always. It tries to help you in your daily life also. Their is a lot of difference between confidence and OVER confidence. I think you have experienced in your life. At last I would like to say that be confident and strong always!