How insignificant are we in the greater scheme of things? I often think abut this.
I'm 5 ft 11, so I'm not too big anyway. Then think about how big your city is, then your country, then the continent, then the world. Move on the solar system, then the galaxy, then the universe!
Right now think about how important what you're doing really is.
Humbling isn't it?
Take a read of this http://dsc.discovery.com/news/2008/02/21/galaxy-hubble-stars.html