Boredom

Boredom is the most painful emotion someone can feel, but it's very easy to remedy and it is usually only felt in small doses.

Horror movies can be very entertaining. Even very sad and depressing movies can be. But, there's never been an entertaining boring movie.

Pain tolerance isn't just about the ability to handle stress and other exhilarating emotions. It's also about the ability to persevere through boredom.

(A person can't feel a quantity of boredom near what they can feel in sadness, stress, etc., so boredom is not the most painful emotion in that way.)