The center of duty is love.
God has given us the singular, powerful and undeserved gift of freedom. There is nothing that we are forced to do; there is always a choice to be made. Do not sully this gift by claiming that duty is dry - emotionless but for a dissatisfied sense of responsibility and reputation. Duty is a choice we make because we love. If this is not the foundation of our behavior, then we are not truly fulfilling what is asked of us by God.