Why do we do everything we do?

Why do we smile at strangers?
Why do we tell our friends we care?
Why do we try not to stare?
Why do we like to make people happy?
Why do we love when we something we say that leaves people laughing?
Why do we when playing board games let the little kids win?

But then again

Why do we pick at our skin?
Why do we do everything we can just to look thin?
Why do we cry every night?
Why do we fight?
Why do we want to see the light?