Just getting ready to move through the high country will get you in good shape! It is a bit of a challenge even for those of us who live 5,000 ft above sea level or more. The higher you go, the thinner the air, like about 50% here on the Front Range to about 70% at 9,000-10,000 ft! So less oxygen and harder to breathe efficiently. Doesn't affect younger folks as much if they are in good shape. We mature
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folks tend to take it very easy when we go higher! Clint looks like he dropped about 50#! For this adventure!
Hawkdancer