people or businesses, I don't know how you could feel good about what you do and keep on doing it. Obviously some people don't care about others so it doesn't apply to everyone... but assuming you do care about others...
Business is just providing a service that is of value to people. You're helping people get what they want and they are happy to buy it from you. As long as what they want is good, and you do it ethically, you should find some degree of fulfillment, however small...