Consider assertiveness, as a random example. People who are very assertive were simply born that way. They were the little 2nd graders bartering for extra candy from the teacher while you looked on, probably rolling your eyes.
Sure, they reap the benefits of being assertive. However, is it really self-improvement when we try to mould ourselves into those we view as “successful?” If a timid person coerces herself to be assertive, does she really reap any benefit?