I was sent to Denver for 2 days to be trained on a new product. (Maybe not new, but new to me). I got in this afternoon, headed to the hotel, and found the hotel gym. They had an outdoor track that I decided to try. Now I don’t jog very often (I don’t particularly like it), but last week I went 1.5 miles on the treadmill, so I figured that on real ground I should be able to at least do a mile. Boy was I wrong. After a half mile I was gasping for breath despite the fact that my legs felt fine. I gave up and headed inside to use the weights and found myself continuing to suffer from shortness of breath. Since I’m too young for a heart attack I tried to find other causes – did I eat too recently? Did I not eat enough? Had I gotten enough protein today? carbohydrates? Salt? Iron? Was it the time change? Was I not breathing properly with each repetition? When I returned to my room I noticed the hotel’s “welcome to Denver” guidebook which gave me my answer – I’d forgotten that I was a mile above sea level! (In the words of Morpheus from the Matrix, “You think that’s air you’re breathing?”). The point of this story is simply that anyone who tells you that the difference in air density at high and low altitudes is psychosomatic is a liar.