When you are truly interested in other people, you will learn what they are interested in and if they have a need for your product. If they like you, and most people like folks who take an interest in them, they'll help you find people who do need what you have to sell, even if they don't.
Zig ZiglarLife is too short to spend your precious time trying to convince a person who wants to live in gloom and doom otherwise. Give lifting that person your best shot, but don't hang around long enough for his/her bad attitude to pull you down. Instead, surround yourself with optimistic people.
Zig Ziglar