Self propelled describes something that moves, progresses or acts on its own power without needing outside help. Like anything else, leadership ability is distributed throughout a population. Can you be a good leader without being a good manager? In my experience, the best leaders are also great managers, and the best managers have strong leadership capabilities.
To be successful, you must have both a passion for improving your organization and the capability to drive your efforts through to completion. Some people are "natural" leaders, others prefer to operate capably within a well-defined context, and many people are somewhere in between. Natural leaders have important core abilities, but they often need careful training in the more practical aspects of converting a creative vision into a concrete program of action. Very often, they need to understand the length of the change lifecycle so they don't underestimate the importance of persistence.
Most people, however, can develop their leadership skills by working at it. The process starts with the recognition that leadership requires "ambidextrous" activities. The first hurdle is recognizing that excellence at the day-to-day is critical, but it is not enough. The second is the need to look inside yourself and decide whether you are willing to be uncomfortable for a prolonged period while you conceptualize and lead the change.
The ultimate reward is the deep satisfaction that comes from seeing something new that wouldn't have been there if you had not created it. Once you decide to become a leader, you can develop the characteristics you'll need by being thoughtful about the accomplishments that you want on your resume, and deciding to devote the time and attention needed to achieve them. Like anything else, practice makes perfect.
To be a great leader, you need a certain level of intellect, but not necessarily great genius. You need a certain level of social skills, but not necessarily those of a great salesperson. However, you do need a compulsion to operate at two levels: to be a great doer, and a great reflector. Most importantly, to be a great leader, you need to find what you really like.
That's where the passion, commitment, and integrity come from. In my experience, the most important underlying factor in leadership is whether a person has searched out and found a great match between what's in his or her heart, which is what he or she really enjoys, and the work situation. Think about the definition of leaders, "people who leave their footprints in their areas of passion." It's easy to focus on the first part, how to leave footprints. But the real power comes from the second, working in your area of passion.