This is a wellknown story:
One evening an old Cherokee told his grandson about a battle that goes on inside people.
He said, "My son, the battle is between two wolves inside us all"
"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".
http://www.psychologymatters.asia/article/65/the-story-of-the-two-wolves-managing-your-thoughts-feelings-and-actions.html
But why do we so easily succumb to feed the evil wolf? Why do we hate and feed it and react hatefull towards others?
Everyone has both good and bad inside of us but it's our decision what to show to other people. Most people hate others because they are envy of what others have that they don't have. Those people chooses to seek for things they don't have instead of being contented with what they have. Hate is sometimes accompanied with anger meaning if a person is mad there's a possibility that they hate you too. Let's not hate and be happy for what others achieved.