Remember, selling at its heart, is nothing more than a transfer of feeling. The most successful sales people in any industry are able to help their prospect to have the same feeling about their product, the same product conviction, and the same kind of enthusiasm about the product as they themselves do.
So, nurture your excitement. Show your enthusiasm. Learn everything that you can to boost your own belief and conviction in what you do. After all, if you're not enthusiastic about your product, who will be?
And, you do own the products you are selling, don't you? How can you be sincerely enthusiastic about the product, if you don't own it yourself.