As I have said many times before, there is something about Katy's voice that has a calming effect on me when I am stressed. What songs of hers do you like to listen to when you are stressed, in order to calm down? There are at least 3 categories of her songs that could possibly have a calming effect:
Ballads, where her soft and soothing voice can calm you down (such as, By the Grace of God, Unconditionally)
Fun songs, that put you in a good mood by helping you forget your troubles (such as California Gurls, This is How We Do)
Inspirational songs, where the message of the song is what inspires you and puts you in a good mood (such as Firework, Roar, By the Grace of God)
What do others think?