"The world responds to action, and not much else."
Many smart people can recognize when there is a problem, but few are willing to expend the energy necessary to find a solution, and then summon the courage to do it. There are always easier ways: give up, accept a partial solution, procrastinate until it goes away (fingers crossed), or blame others. The harder way is to take the problem head-on and resist giving in to conclusions that don't allow for satisfaction of the goals. Successful project managers simply do not give up easily. If something is important to the project, they will act aggressively—using any means necessary—to find an answer or solve the problem. This might mean reorganizing a dysfunctional team, getting a difficult room of people to agree on goals, finding answers to questions, or settling disagreements between people.
Sometimes, this means asking people to do things they don't like doing, or raising questions they don't want to answer. Without someone forcing those things to happen, the easier way out will tend to be chosen for you. Many projects consist of people with specialized roles who are unlikely to take responsibility for things that are beyond their limited scope (or that fall between the cracks of their role and someone else's). Perhaps more problematic is that most of us avoid conflict. It's often the PM who has to question people, challenge assumptions, and seek the truth, regardless of how uncomfortable it might ...