I'm Too Cold

I'm way to cold in this classroom to focus right now.  However, I am always cold.  No matter what I do, I'm cold. I hate the winter, because I'll be outside for .1 second and I'll be shivering.  Once I start shivering, I can't stop. I'm able to go outside during the summer in a sweatshirt and jeans and I'll be perfectly fine.  I think there is something wrong with me.. HELP.