for me, part is about cleansing your senses of highway, tv, and electronic sounds, and substituting that with natural sensations. Like the sound and feel of wind, the sights of lakes and green meadows, and the smell of trees and plants. All the sights, smells, and sounds of the mountains are clean and pure, and refreshing. Even breathing the air is delightful. I have to say I don't sleep very well, but I love the cool air and being warm in the sleeping bag.
Besides the immersion of the senses, there is a calmness to walking. I think my walking takes me to a place somewhat like people who find peace in meditating, chanting, yoga, running, or cycling. I feel peaceful and calm when walking. Even walking uphill, I seriously feel like I am floating, with no effort at all. I used to attribute this feeling to being in great shape, but I'm not in great shape anymore, and I still feel like I float up the trail. Maybe this is the zen that Buddhists seek through meditation, and would explain why I get antsy when I have not been out hiking for awhile.
In actuality, the discomforts are either not that big of a deal, or are just different ways to experience nature. The cold of the morning is balanced by a hot cup of coffee. The hot of the day goes well with a snocone made of snow and coolaid. The blister on the foot, the mosquitoes, scraped knee, are really quite minor issues. The feeling of sweat and grime is easily taken care of by a dip in a lake, and that invigorated feeling when coming out of a cold lake is hard to replicate in town. If people can't figure out a comfortable way to poop in the woods, they are not very imaginative.