I first saw this shared on SR. There are varying versions of it, and no verification that it actually came from an old Cherokee. Still, it's valuable:
"An old Cherokee is teaching his grandson about life. 'A fight is going on inside me,' he said to the boy.
"'It is a terrible fight and it is between two wolves. One is evil - he is anger, envy, sorrow, regret, greed, arrogance, self-pity, guilt, resentment, inferiority, lies, false pride, superiority, and ego.'
"He continued, 'The other is good - he is joy, peace, love, hope, serenity, humility, kindness, benevolence, empathy, generosity, truth, compassion, and faith. The same fight is going on inside you - and inside every other person, too.'
"The grandson thought about it for a minute and then asked his grandfather, 'Which wolf will win?'
"The old Cherokee simply replied, 'The one you feed.'"
I have that posted near my desk. I don't always succeed at following its wisdom. But I try. It helps.