Bad: Getting on the subway to go home instead of going to class because you're feeling sick, only to discover that every noise makes your headache worse and every smell makes you feel like you're about to throw up.

Good: Making it all the way home without throwing up and having a nice evening at home.

Bad: Coming into work the next day and having the headache and nausea reactivated by being forced to listen to a coworker eat loudly at her desk.

Grr.