I think so. Even if you train yourself to behave like a leader if the situation required it you will always go back to your natural behaviour. Besides, you can accepted your personality because everyone must value their own qualities. In this world there is a place for everyone, so you have to focus in your aptitudes and strengthen them.

Spending time in classes, writting, reading, listening but no speaking is not the best way to improve this skill. As a shy person is difficult to me go on with my speaking. But I don't give up, and I hope to improve my English once and for all.