Always know the end of a business venture before you begin. Plan for it and don't lose sight of it. While it may seem paradoxical, the end will one day come and you need to know your exit strategy before you step through the door.
Are you planning to build a business that will give you a good living until retirement? Are you planning to build an international enterprise that will not only support your lifestyle, but effectively financially position your children's children? Are you intending to build the business to a certain point, sell it, and move on? How does your venture contribute to your vision of life in ten years, and when will the time come for you to part ways? What will be the key indicators that will signal that the end is near? Knowing how the story ends is key to determining how it will begin and how decisions will be made as the business grows.
If you're thinking about starting a new venture, or diversifying your corporation in new directions, or buying a new enterprise to complement the holdings you already have, take a long look at how you picture the end of the road. I recommend reading Start With Why by Simon Sinek, or Business Stripped Bare: Adventures of a Global Entrepreneur by Richard Branson. Make sure you know where you're going, why you're going there, and how you will know when you have arrived. And when the time comes, execute the exit strategy you have always planned.