Some people just hike. I'm one of those hikers. I bring what I need and if it's too much weight to be comfortable, I start pulling out the stuff that isn't really needed.
Some people hike but strive to carry as little weight as possible.
There are different degrees of 'ultra-light' hiking.
Often times a person gradually shifts from a regular hiker to an ultra-light hiker over time.
As their equipment gets old or worn out they'll either simply not replace it and do without, or they will replace it with something lighter than what they used to own. Over time, doing this will gradually lighten your pack.
Some people limit thier pack to the 10 essentials and nothing else. Plus they try to make sure their Essentials are as light as possible.
Others trim their 10 essentials down to 9... or 8... or 7... or less.
Other Ultra-Light hikers take this a step further. They cut off excess straps from their pack. Replace zipper pulls with (lightweight) fabric. Shorten their shoelaces. Shave their beard. Wear half shirts.
Underwear? It's just a disposable convenience item that adds unnecessary weight.
Like I said, that's not how I roll.
I did however, have a portion of my toenail removed this afternoon.
For the records, it was done for a medical purpose and not at all in an attempt to be 'ultra-light'.
Some of you hikers may find these toenail care instructions useful.