Jethro was delighted when he heard about all the good things the Lord had done - Exdous 18:9
Paul: "be happy with those who are happy" - Romans 12:15
Jethro, Moses' friend, celebrated with the people of Israel: "Praise the Lord, for he had rescued you from the Egyptians - Exodus 18:10
He immedidately blessed those around him with words of praise
The same thing can happen when you share in another's joy over God's kindness and blessing