Dude, you forget one thing, you were much younger and had much more stamina at that age. I got "volunteered" to carry the squad mortar baseplate for a couple of quick jaunts out of AIT. This was along with the basic M-14 and all the assorted gear that goes along with a jaunt or two. It wore me out and I was bitching every step of the way going just a "hill and dale" or two.