Buddhism and self-improvement

For a person to have a will to change, there must be some dissonance between its real self and a mental image of ideal self. To put simply, one must be dissatisfied with oneself somehow. This dissatisfaction, or "unacceptance", is the driving force that push people toward better, however they define it. Let it be a stronger physique, better social skills, greater knowledge, better money management, whatever. One can think that such unacceptance of one's flaws is a good thing. But here comes Buddhism, and tells you to 'let it go'. To stop focusing on your flaws, to stop creating mental images of yourself, to accept the world (including yourself) as it is. (I say generally 'Buddhism', since I believe this teaching is universal, although I was exposed to Zen mostly) Now the question: **how does Buddhism reconciles the teachings of dropping the ego with having goals to improve ones flaws?** It seems contradictory to me, as I assume it's impossible to work on my flaws without focusing on them and relating them to the image of myself, which I'm supposed to drop.