Knowing both is important. Do you crave working without a boss? Want to make your own hours? Do you have an innovative idea for a product? Do you want to offer better service than your old employer? What will your ideal small business be like?
Make a plan and then make future decisions with your real goals in mind. They will keep you inspired and save time.
Remember that you will be responsible to your customers or investors even when you are your own boss. How will you make that work?