When deciding whether to be kind, the default position must always be to be kind. I have never regretted being kind to people but there were times when I felt I could have been kinder.
People seem to want meaning in life. So much meaning can be had when you do something nice for someone else without the expectation of repayment. Even if the gift isn't appreciated, your act of benevolence is something to be proud of on a personal level and a standard to aim for in a refined individual.
Be the creator of good and you might find yourself surrounded by the goodness you exude throughout the day, each and every day.