Why do some people suffer with SAD while others don’t?

Hello everyone- I am new to this sub but not new to SAD. I have suffered with it since I was a teenager- now in my mid 30s. Every year from November to March it feels like a heavy weight is on me. I’m sure a lot of you can relate. For years when I would express this to others it was always met with “meh- I feel fine. you can’t control the weather! Just get over it! Just go on a walk!” I live up north, the days are short and dark. Winter is cold, grey and overcast. The only time I feel somewhat alive is when the sun is (rarely) out or if there’s a nice snow (I think the snow makes it brighter outside so it helps my brain “wake up” more?)

Anyways, I just a wondering why some people suffer from SAD but others don’t? It’s really fascinating. Most people around me do not suffer in the way I do. Why does the weather/light affect us so much compared to others? Whats everyone’s thoughts on this? Thank you for reading.