"Whatever you do, do from the heart, as for the Lord and not for others, knowing that you will receive from the Lord the due payment of the inheritance. You are serving the Lord Christ."
Your job will certainly be easier and more rewarding if you imagine your customers and co-workers as Christ Himself. By putting your heart and soul into your work, you are, in a sense, imitating Christ as you serve Him and others. Our ultimate inheritance is eternal life in heaven, a goal to keep in mind each day.