When my sisters and I would fight as kids, my folks had us recite Ephesians 4:32 -- in the Authorized Version, of course: "And be ye kind one to another, tenderhearted, forgiving one another, even as God for Christ's sake hath forgiven you."
More recently I noticed something that gives the word "kind" specific content. This word is also used in Matthew 11:30 when the Lord says, "My yoke is easy." Kindness asks, "How can I make this situation as easy for the other person as possible? How can I avoid embarrassing this person, putting this person on the spot, cornering this person? How can I make a positive response as easy as it can be, even if I have to absorb the difficulty into myself?"
Beautiful word, costly deed. The price of love.