If you help someone and it results in a smile and a thank you, that makes both of you feel good. And feeling good about ourselves is what we humans strive for isn't it?
The selling environment is no different. If you feel good about helping a customer achieve his or her goals you are personally rewarded by feeling good about yourself.
Think about how you feel if you sell your customer something they don't want or need and they call you to return the product. How does that make you feel? Probably rejected and not very good if you have any conscious at all. Moreover, what do you think that person will say about your product, your business, or you as a business person? It will probably not be good. It is often said that if a product is good the customer tells a couple of their friends. If the product is bad, they tell all of their friends. In business, you don't want to be 'that guy.'
You need to keep this in mind - People don't want what you are selling but they will buy what will help them achieve their goals and desires. People do like to be sold to however. They like to be treated fairly and have their needs met. And they also like to spend money on new and different things that provide them with value or make them feel good about themselves. You should always look at it from the viewpoint of the customer and how can you help them. As Dean Reick states in his 12 tips for Psychological selling: You can't force people to do anything. When people buy, it's not because you wield some magical power over them. You can urge. You can push. You can entice. But ultimately, people do what they want to do. This means your job is to show how what you're offering meets your prospect's needs.
A great analogy is this: Thousands of 1/4 inch drills are sold every year, however people don't want a 1/4 inch drill, they want a 1/4 inch hole.
So strive to help others achieve their goals, that's where the rewards are.
Let each of you look not only to his own interests, but also to the interests of others. - Philippians 2:4