When I started Jump School in 1988, I weighed 130 pounds. When I graduated, I was down to 114 (run everywhere for three weeks straight and you'll lose weight too).
On my second jump with the 82nd Airborne, however, I weighed well over 300 pounds going out the door (Honduran border, March 1988). This included myself, my parachute/reserve, my rifle in its case, my helmet and flak vest, my web gear and ammunition, surveying instruments--I was a Field Artillery Surveyor then--tripods, survey stakes, tools, batteries, workforms, manuals, etc. all in my backpack. My personal gear consisted of a mechanical pencil, a towel, three MREs and a poncho liner. I would have shed the weight of the poncho liner, but the instruments needed the padding.
Just running the 300 yards to the assembly area darn near did me in, and I was in the best physical shape of my life.
It didn't take me very long to learn the value of packing only what I needed, because mission requirements took up all my pack space.
Now I'm in Iraq. I'm not a FA Surveyor anymore, but I still have to lug around my helmet and "improved" flak vest, which weighs about 18 pounds more than the one I wore in the 80's (it's truly bulletproof, though, which I suppose IS an improvement). I also have to carry ammunition and now, since I'm also the M203 gunner, my rifle's heavier and I have to lug around the grenades for same. I'm also my team's Combat Lifesaver, which means I get to carry the medical bag, too. Oh, and I can't forget the water. Can't carry too much water here (as I write, the temperature is a pleasant 105 degrees outside, down from a high of 134).
The fact is that I simply CAN'T carry anything extra and hope to function. I MUST pare down. My "backpacking" gear consists of what I can fit into about half a buttpack's worth of volume.
When I'm home, I'm a ham radio operator, and the lighter my pack is; or rather, the lower the volume of stuff in my pack, the more room I have for radio gear. Backpacking for me is simply a means to an end; namely, getting to wherever the activity I planned is.
My habit of "travel light, freeze at night" was hammered home to me by experience, and now serves me when I simply want to be outside and enjoy myself. I know no other way to camp.