As Yogi Berra once said, "You've got to be very careful if you don't know where you're going, because you might not get there." Projects usually get the go-ahead for good reasons, but the motivation for a project may be barely sketched out when the project begins. Before you can work out the details of how you'll perform the project, you must identify what the project is supposed to achieve.
Dr. Joseph M. Juran's definition of a project is a problem scheduled for solution, so identifying the problem to solve is usually the first step. A project mission presents the problem in a way that makes people care. Because most problems have more than one possible solution, the project strategy outlines the solution you've picked. From there, you identify all the goals for the project, the results it will deliver, and the assumptions you've made in preparing the plan.
When you start to identify the problem to solve, your colleagues turn into hypochondriacs, overwhelmed with symptoms and making wild guesses at the underlying problem. Just like antibiotics don't help when you have a virus, the right solution to the wrong problem is still wrong. As project manager, your job is to tease out the real problem from the project sponsor, customer, and other stakeholders.
Most people offer solutions instead of describing the actual problem. For example, suppose your CEO says the problem is that the company doesn't have a TV commercial. You could start planning to ...