Tell me a story
Everyone carries an invisible bucket. 
When the bucket is full then we are happy. When it is empty then we are sad. 
The interesting thing is that we can only fill the bucket by doing good deeds and helping others. When I do a good deed to someone, my bucket gets filled but so does the other person's bucket. 
When I do a bad deed to someone, then my bucket empties and also the other person's. 
So, as long as we all keep filling each others buckets, we can all be happy