I used to be bothered by the cold, but now I'm not. Now, I can walk up to work in 4 degree weather like it's nothing.

I'm unsure why exactly, but I have a theory.

There was actual research done that showed that somebody who feels lonely has a reduced body temp. This is because, back in the early days of humanity back when we lived in tribes and villages, being banished from the tribe typically meant certain death. Therefore, feeling cold was a response to being away from the tribe.

I think that because of how alone I've been my whole life, I have adapted by feeling cold all the time. I think that my resilience to the cold weather has increased as a result of prolonged loneliness.