Training in higher altitudes

I live in a place where the elevation is only 150ft Above sea level.  I have trained in the low mountains of Iraq, with minimal effect on me as far as oxygen intake to my body.  I have trained in Afghanistan at an altitude of 6,000ft.  Where I noticed a real difference in my lungs when I would get on the elliptical and do some cardio my lungs and nose were on fire from the thin air.  Then I make it to Colorado Springs I heard of this place called the incline and was told you must train to even attempt to climb it for training.  People called me crazy when I told them I was just going to go climb it and maybe even run it.  I told them "I am already trained".  Well I went and climbed it one afternoon a couple weeks ago and I will say it was intimidating.  When I started climbing only about a quarter of the way up i was gassed in a bad way!  I was only climbing 1 1/2 miles up but the altitude change is something crazy like 2,800 ft!  I finally got to the top of this peak and the view was amazing!  Persistence and a mental focus got me there.  If you ever have the chance to train in higher elevations I highly recommend it.  It will not only make you feel less of a human but it will make you train harder then what you thought you was previously training.  If you can't get to higher elevations then hit the stairs at a local stadium or go find a big hill to run up.  It will build the strength and endurance in your legs and build your mental strength for pain.  So go find you a big hill or mountain to climb and don't stop until you get to the top!