Common Business Owner Mistake #4. It’s only human to fantasize about how you’re going to spend your time and money after selling your business. But while you’re dreaming of all the exciting changes to come, be sure to stay grounded in business fundamentals, such as pursuing new opportunities, making important strategic decisions, and adequately taking care of customers. It may take upwards of a year to sell your business, and no one wants to buy a company in decline. The fact is, this is a marathon race, and you need to give it your all until you cross the finish line.