Kindness has so many positive outcomes, it heals emotional wounds, it can mend relationships, and is a respectful and honorable way of living. Beyond that it personally helps the person who is being kind two-fold.
In my own experience, choosing to be kind has always brightened up any situation, especially with my fiancé, choosing to be kind even when it is not the easiest has almost immediately stopped any fight we were in, and doing things to help out of kindness has improved our relationship more than I know.
Beyond that choosing to serve people we do not come into contact with out of kindness helps also, my fiancé and I go to a homeless shelter often to help out and we are addicted to doing it, we do not gain any from it except the joy we get from serving others. We feel like we are a better because of it, we always leave feeling more rejuvenated and feeling like we made a difference.
I encourage everyone to try to be kind today, even when it seems like the last thing that you want to do it, it will benefit you more than you know.