Miyagi wouldn't have said it better

"But he also said something else...
Ah, I was afraid of that!
Carlo ignored the interruption, and his face glowed with sudden ardour.
...That there's only one corner of the universe you can be certain of improving and that's your own self. Your own self, he repeated. So you have to begin there, not outside, not on other people. That comes afterwards, when you've worked on your own corner. You've got to be good, before you can do good - or at any rate do good without doing harm at the same time. Helping with one hand and hurting with the other - that's what the ordinary reformer does.
Whereas the truly wise man, said Eustace, refrains from doing anything with either hand.
No, no, the other protested with unsmiling earnestness. The wise man begins by transforming himself, so that he can help other people without running the risk of being corrupted in the process."

Aldous Huxley - Time Must Have a Stop