As was pointed out elsewhere in these comments, there are situations where changing "what you are" - for example, increasing your confidence levels - is more effective then trying to change your actions directly.
Let's say that you don't do something that you want to do, because you're not confident enough.
What is the difference between doing that thing, and improving your confidence which causes you to do that thing? What does it even mean to distinguish between those two cases?
And if improving your confidence doesn't cause you to do the thing in question, then what's the point?
Edit: On a reread, I might interpret you as saying that one might try (but fail) to change one's actions "directly", or one might attack the root cause, and having done so, succee...
Happy New Year! Here's the latest and greatest installment of rationality quotes. Remember: