What songs cheer me up? Quite honestly, I tend to listen to melancholy classical music if I want cheering up, as a way of riding out the mood, so to speak. Think Mahler's 5th Symphony, Aram Khachaturian's Gayane: Adagio, Beethoven's 7th (2nd movement), or something more modern like John Tavener's Funeral Canticle. Or perhaps a really melancholy film score like Gabriel Yared's compositions for The English Patient and The Lives of Others.

I only opt for pop if I'm already in a good mood.