My kit weighed easily about 70 pounds and I didn’t have to carry the real heavy stuff since I was never more than 100m or so from a Stryker.
I have some knee problems, but they tend to dissipate if I take chondroitin steadily for a few days. I really feel bad for the Afghanistan light infantry guys carrying all their gear up and down mountains. That’s gotta hurt.
That is an immutable Law of War.