If you understand PERSPECTIVE, command it and control it, then there is truly nothing you cannot do; since what one believes in heart, becomes reality in the space of your mind. It may not be someone else's perceived reality, but if you can convince yourself, then it becomes truth to you.
Insane people have long demonstrated this as delusion, but used correctly it can become a powerful tool. I am not talking about bending reality necessarily, but taking a moment to view everyday life and what is going on around you, in a way you WANT it to be. In bad times it takes more effort then in good, however, in most situations there is hope, motivation, a lesson and some joy.
For myself it provides comfort to pause and take a moment to approach my thoughts from the opposite viewpoint, both positive and negative, the ultimate self-critical devil's advocate. Most decisions become clear with this approach. If you can involve a like minded partner the method can become even more powerful.
For an anal perfectionist looking for truth, constantly flipping 180 degrees in your mind changes perspective quickly.