A major theme of this book is that leading a project is, first and foremost, about people ” involving them actively to achieve goals and objectives. Without their involvement, no project is possible. Effective project managers know how to make this happen and the secret is motivation. The importance of motivation is often overlooked or trivialized, causing needless frustration and anger, even for project managers. As William Cohen observed in The Art of the Leader , leaders often fail to understand what motivates their followers and, if they do, they misconstrue what the real motivation is. 
Many project managers hold a common feeling that they lack power over people and, therefore, cannot get people to do their bidding. Nothing could be further from the truth. Project managers have considerable power to influence, although not necessarily control, people. Even seasoned executives with substantial power will admit that the more one tries to control in the traditional sense, the less they actually do.
One of the biggest failures by project managers is to not consider the "people factor" very seriously. Ultimately, this failure results in sliding schedules, exceeding the budgets , and poor quality of output. However, these are only indicators of a poor understanding of people. What is the real contributor ? It is a mismatch of a person with his or her task and relationship with peers. In other words, no synchronicity occurs among personality, commitment, and assigned work.
Some consequences are quite common, some controllable and others not. A common consequence is a prevalence of negative emotions, e.g., fear, anger, frustration, and anomie. These emotions lay the seeds for "bad" performance, such as rework and needless oversight, greater turnover , and sick time. In time, the stress can mount to a point that involvement declines. On a much larger scale, negative conflict destroys teaming and power struggles arise over tasks , even for the position of project manager.
 William A. Cohen, The Art of the Leader , Prentice Hall, Englewood Cliffs, NJ, 1990, p. 139.