Live in a forest or jungle so you are always breathing the best source of oxygen (produced by your pet trees and other plants).

Also, don't forget about our microbial friends!

[link to photosynthesiseducation.com (secure)]

"Photosynthetic bacteria are currently being used in various applications which include water purification, bio-fertilizers, animal feed and bioremediation of chemicals among many others. They are used in the treatment of polluted water since they can grow and utilize toxic substances such as H2S or H2S203."

What are we mostly composed of?

Water.

Spirulina spiritual war paint, anyone?