The most successful salespeople commit. The best-of-the-best salespeople believe in their companies. They believe in their products and services. They believe in their customers. But most of all, the most successful salespeople believe in themselves and in their ability to succeed. There is a direct relationship between the level of belief you have in yourself and your product or service and your ability to convince other people that it is good for them.
The profession of sales has often been called "the transfer of enthusiasm." The more enthusiastic and convinced you are about what you are selling, the more contagious is this enthusiasm and the more your customer picks it up and is eager to act on it.