"If someone tells you what they wish they would have done, listen. If they only tell you things they wouldn't have done, ignore them, because they've confused regret with wisdom. When someone fantasizes about having achieved less in life instead of figuring out how to make things better, that's more of a review of the life than the problem. Even when they're right about the problem, they're the wrong person to help you solve it."
Second, the rifle prayer from Full Metal Jacket (or something very similar):
"This is my rifle. There are many others like it, but this one is mine. My rifle is my best friend. It is my life. I must master it as I must master my life. Without me, my rifle is useless. Without my rifle, I am useless. I must fire my rifle true. I must shoot straighter than my enemy, who is trying to kill me. I must shoot him before he shoots me. I will. Before God I swear this creed: my rifle and myself are defenders of my country, we are the masters of our enemy, we are the saviors of my life. So be it, until there is no enemy, but peace. Amen"