Lack of confidenceWatch
It is hard, and it takes a long time, but if you work on it you will improve. For me, 10 years ago I was terribly, terribly shy. Today, I am not. The way I changed was to force myself to do things that made me feel uncomfortable, and do them regularly. For example, I started practising aikido. I trained for a while, then I became good enough to lead warm-ups and help teach others, and now I have an instructor's licence and teach classes in my own right. I did a lot of things that were difficult and uncomfortable, such as moving abroad for a year, meeting new people, deciding on certain life goals and orienting my life around them, and so on, that forced independence from me.
The way to confidence is to marshal yourself into a situation where confidence is an inevitable by-product. You need to put yourself in a position where you are forced to be social and do things that demand confidence. After being in enough situations with enough regularity, you start to notice how much you have improved.
The difficulty is in finding ways to force yourself, because you will not want to do any of it in the beginning. My advice is to make it as difficult to get out of as possible, because if you rely on motivation, you will fail whenever you are feeling unmotivated. In my case, I tend to find making commitments to others works well, since I don't like to let people down. Try to find out what works well for you and keep at it. If you take self-improvement seriously, you can achieve a hell of a lot.