Why Do Some People Shiver When They Are Cold, But Others Don’t?

Shivering is when your body shakes to keep warm. Some people shake a lot when it's cold, and others barely move at all. It depends on how their bodies work, like if they're used to the cold or not.

Imagine two kids outside in snow: one is wearing thick clothes and stays still, while the other runs around with bare hands. The first kid doesn't shiver much because their body keeps them warm, but the second kid shakes a lot because their body is trying very hard to keep warm.