There is always some driving force for whatever one does. It is this force which keeps one working for any cause or goal. I may be putting all my efforts for a cause due to some pressure or desire for material gain or some kind of faith (religious, ideological, etc.). I observed, that is the case with many of us very often. Second possibility is that I might be doing something due to my understanding/conviction or self realized interests or motivations. The first one is very much influenced by external factors while the second is originated from within. Let me first take an example to differentiate between the two.
There is a student who has to make a choice between science and arts. The guy is equally good in science and arts but his natural interest is in arts. Therefore, quite understandably, decides to do his further studies in arts. When his parents come to know about his decision, they try to persuade him that since there are many more opportunities in science and better social status for science graduates, he should go for science. His friends are not supportive either. But, the guy ultimately listens to his heart and goes for his genuine interest. This is what falls in the second category of driving force. If he would have been lured by physical gains or succumbed by the peer pressure, this is what falls in the first degree for driving force.
One might wonder what difference does the driving force behind one's action make. The general understanding is the theory of 'whatever works'. If I am successful in whatever I choose to do, nobody is going to ask questions. Many times, it may not be very difficult either to achieve a reasonably good level in your field without having genuine interest in it. But, then comes the question of satisfaction and joy. Furthermore, can I achieve excellence in my work without enjoying it?
Under the influence of first kind of driving force, I enjoy the benefits for which I started pursuing the goal, like status, money etc. But after some time, I start looking for my participation and role in the bigger part of the system, which is very difficult to identify if I am not doing what I really want to do. If I can't find it, I can't really maintain my dedication for long because I can't see my specific importance in the system. It leads to a feeling of unfulfillment and ultimately, dissatisfaction.
On the other hand, right understanding and self realization lead to the understanding of myself, entire existence and thereby, my role into it. Once I can see the bigger picture, I use my creativity and imagination to find myself an appropriate role to contribute to the bigger units of order, i.e. family, society and nature. I can recognize my importance in the larger system and hence feel responsible for it. Whatever I do is just a medium of performing my responsibility which I can choose or find according to my interest.
For example, there is an ordinary office worker. If he can see his importance in the overall system, he does his work with the sense of responsibility. Once that sense of importance and responsibility is lost, he is just working due to some fear of being punished or material loss; he looks for the short cuts and the ways to escape his responsibility. Therefore, the driving force affects the continuity of performance, motivation and dedication towards the cause. I work only if I enjoy it otherwise I am just made to work, i.e. a slave, a state which is not naturally acceptable to any human being.