Your friend is the exception, I think. I’ve not lived below 5000 ft for over a decade, and every time I get to sea level, I feel like I can run FOREVER. My pers

Your friend is the exception, I think. I’ve not lived below 5000 ft for over a decade, and every time I get to sea level, I feel like I can run FOREVER. My personal records are all from those types of trips.