That is a great thing to make sure you have in your business plan, that your business will be built around those real customer wants. Do not make callous assumptions, or statements like "I know what people want", "People are going to love this", and so on. Have you done your research? Do you really know that the people you will be targeting want your product / service, and crucially do they want it AT THE PRICE that you will be offering it at? Whilst confidence in your plan is fantastic, you must make sure that it does not lead you down a blind alley along a path that is not desired by your target market. Don't assume what customers want, do your research and make sure that is clear from the start in your business plan.
When you're writing a business plan in a situation like these, you need to address a few issues the intentional entrepreneur has already pondered. The first is do you really want this idea to become a full_blown business? Certainly it's flattering when you realize there's a market value for something you were doing anyway, but that doesn't always mean you should launch a business. A lot of accidental businesses form around fads or seasonal items, and may not be robust enough to function as year_round, money_making, enterprises.