Actually guys there is a method of breathing that may help increase your stamina I talk about it in my follow up post to the, "Training injuries: causes and cures" thread.
I will summarize.
Diaphragmatic breathing is a technique where you breath in through the Nose and Out through the mouth paying carefull attention to breathing deeply enough to accomplish Both chest and Belly breathing at the same time. The breathing must be deep But relaxed ( No hyperventilating).
This type of breathing has Been shown to increase tidal Volume as well as Blood Gas exchange In the lungs.