Get to know yourself. Know your own failings, passions, and prejudices so you can separate them from what you see. Know also when you actually have thought through to the nature of the thing with which you are dealing and when you are not thinking at all... Knowing yourself and knowing the facts, you can judge whether you can change the situation so it is more to your liking. If you cannot--or if you do not know how to improve on things--then discipline yourself to the adjustments that will be necessary.
Bernard Baruch