Happy Or Sad?
The way you arrange a song can really change it. Take a sad song and play it up-tempo and it has a whole different feel to it. Or, play an upbeat tune with just an acoustic guitar and slow it down...and you might start crying (just kidding).
Listen to these examples of some popular songs changed from minor chords to major chords or the other way around and....You know what? Too much theory? Just listen -- and no crying!