I don’t know the source of this story, but it certainly rang bells for me!
An old man was teaching his grandchildren about life.
He said to them, “A battle is raging inside me … it is a terrible fight between two wolves. One wolf represents fear, anger, envy, sorrow, regret, greed, arrogance, self-pity, guilt, resentment, inferiority, lies, false pride, superiority and ego. The other stands for joy, peace, love, hope, sharing, serenity, humility, kindness, benevolence, friendship, empathy, generosity, truth, compassion and faith.”
The old man fixed the children with a firm stare. “This same fight is going on inside you, and inside every other person, too.”
They thought about it for a minute and then one child asked his grandfather, “Which wolf will win?”
The old man replied: “The one you feed.”