Because suffering can be good for you.

MTH131 quiz 4 is the most disgusting quiz I've ever done. I want to just die and rip the stupid paper with the questions on them up. I can't solve the questions!

But I must remember that sometimes suffering is good. It makes you aware of stuff. Like what Wenfu said, if you put your hand on a boiling hot kettle and you don't feel any pain, you would continue leaving it there and in the end, your entire hand will be burnt and probably die. Whereas, if there was pain, you would have had removed your hand. So the suffering initially is good!

The pain of having to go through quiz 4 is good (or so I would like to think). It made me know how much I have to study for my finals.