Some people think that since one's self-image is largely based on how parents, teachers, and friends treated them when they were young, they can do little to change their self-image. But this is wrong.
It is true that our self-image is based largely on our past. But what counts is how we judge ourselves in the present. Regardless of how we were considered by others, we have the ability to change our own attitude towards ourselves.
Imagine that a monarch's young son was captured by bandits and raised by them. They treated him as a lowly servant and that is how he viewed himself. At the age of 25, he was returned to his father the king. His attitude toward himself will be transformed almost immediately. The prince now realizes that his original view of himself was based on a mistaken notion and he will now view himself as a member of royalty.
This is the Torah evaluation of human beings. Every person is created in the image of God. We are all nobility and should view ourselves accordingly. Lowly self-images are based on mistaken notions - and we all have the ability to change those notions if we choose.
Once you internalize this concept, you can look back at your past experiences and picture how you would have dealt with difficult situations if you would have had a positive, confident attitude. Don't look back with regret. Rather use this as a tool to rewrite, as it were, your past history. This will have a powerful effect on all that you do in the future.
(Gateway to Happiness, p.119)