It comes down to acclimatisation. For instance, as a kid I was used to paddling in the North Sea. Then we went on holiday to see some relatives in Germany and there was a pool fed from a glacier and my sister and I were splashing in it and locals were going "don't they find that far too cold?!?" My body is acclimatised to deal with a "comfortable room temperature" of about 20 degrees. If I had grown up in a country where the normal room temperature was 40 degrees, it might be a different story...