" It is easy to be calm when there is nothing to worry about, Eragon. The true test of your self-control, however, is whether you can remain calm in a trying situation. You cannot allow anger or frustration to cloud your thoughts, not at the moment. Right now, you need your mind to be clear.
Have you always been able to remain calm at times like this?
The old dragon seemed to chuckle. No. I used to growl and bite and knock down trees and tear up the ground. Once, I broke the top off of a mountain in the Spine; the other dragons were rather upset with me for that. But I have had many years to learn that losing my temper rarely helps. You have not, I know, but allow my experience to guide you in this. Let go of your worries and focus on the task at hand. The future will be what is will, and fretting about it will only make your fears more likely to come true.
I know, Eragon sighed, but it's not easy.
Of course not. Few things of worth are. Then Glaedr withdrew and left him to the silence of his own mind. "

― Christopher Paolini , Inheritance (The Inheritance Cycle, #4)