The Apostle Paul says kindness is a choice. It is something we can choose to "put on" every day. Kindness is "love in action" -- a practical expression of love. It is visible and active, not just emotional.
Colossians 3:12
Therefore, as God's chosen people, holy and dearly loved, clothe yourselves with compassion, kindness, humility, gentleness and patience.
The poet Robert Burns said "The kind heart most resembles God."
Proverbs 21:21 says, Be kind and honest and you will live a long life; others will respect you and treat you fairly.
Now, that's a promise to hold on to! Go and kill 'em with kindness.