How? Well, for starters, don't forget to blink. If you don't blink every few seconds, your eyes are going to dry out. Are you making sure to blink?
Also, when was the last time you took in a good, deep breath of air? just INHALE all of that air, fill your lungs with that oxygen. One huge problem though.. Through respiration, you need to exhale that CO2. So go ahead and exhale that air in your lungs.
It's important that you blink and breathe. I wouldn't want your eyes to dry out or for you to pass out from not having air.