Why does emotional pain manifest as physical pain?

Whenever I’m really sad it feels like either heartburn, or this “tightness” or something just below my sternum.

Also Creamsicle says he’s sorry for making a dumb post. Here’s a picture of him with a noodle on his head.

Btw I take him to the vet when he eats cat food because that’s Gregory’s cat food. I tell the vet he got into some chocolate so they’ll give him an emetic and maybe he’ll decide the cat food isn’t worth it and there won’t be a next time, but he’s an idi—GOD DAMNIT CREAMSICLE COME BACK HERE.

”Yay!”