I have treated many clients with low-confidence, self-esteem and self-image issues for many years now.
These issues can severely affect our relationships with friends, family and co-workers. I have seen many people get into bad relationships simply because they have found someone that cares for them - initially! I have seen others who once in a relationship get very concerned about continuing to seek approval from their partner - and when that doesn't happen, they get very concerned about themselves and the relationship. Low self-esteem, lack of self-confidence or self-image issues do not necessarily involve people being "shy" or passive. In many cases, these individuals behave compulsively as a way to protect their low self-image, or they may be overly active, trying to compensate for low self-esteem.
Often people with low self-esteem have difficulty really accepting compliments or praise. Either the compliments are not heard or are viewed with ulterior motives, or they crave complements. In this case, the complements are like an addictive drug - there comes a time where the amount taken-in must increase in order for the person to continue to feel good about themselves. Therapy often simply addresses how people with low self-esteem function in the world, and how they get into situations that foster these feelings. The goal is not to show a client that they are worthy, but to have the client come to the realization themselves.