Feeling of Pleasure vs Feeling of Pain

I am totally addicted to chili. Fresh chili, that is. I just love it. But why is it that us human beings don't know when we've reached our limit?

I remember once, in Ghana, when I decided to eat a mixture including lots of fresh chili. I was warned by my husband and the house keeper, and still I ate it. It was lovely.

But the next day it wasn't lovely anymore. I was sitting on the toilet crying from a burning pain in places you don't want a burning pain.

And yesterday I did it again. My husband and I went to a nice Thai restaurant in Vasastan, Stockholm. (It's called Narknoi if anyone reading this would like to go there.) As I'd been there before I knew exactly what I wanted for a starter. They have this really nice, and really hot cucumber/lime/chili salad. I just had to have it, even though I could clearly remember what it had done to me the last time.

I ordered. I ate. I cried. Snot was running. Sweat was running. And I could barely speak for 15 minutes as my tounge felt all swollen. I was in pain!

So, what is it with us people? Why is it that I know that, even though it's painful, I will order the same salad the next time too? Is the feeling of pleasure (the lovely taste I mean) so much stronger and more memorable than the feeling of pain?