I think I understand some of what you said…
I’ve read, for example, that most native people who inhabited my current homeland wore just a buckskin loincloth (men) or apron (women) pretty much year round despite temperatures that require me to bundle up. The kids repordedly went naked most of the time.
How did they do it? Conditioning themselves over a long time, rubbing fats into their skin, toughing it out, staying near a fire when cold unless they had to leave it… Those things and others probably helped but all this information comes from what I learned from others, not first hand knowledge.
I like wearing skins or pants and a shirt and shoes when exploring dense woods even when the air feels warm, so branches and thorny vines, brambles and other sharp things dont cut me up.