The ability to accept and recognize one's present state of being as adequate seems to me to be a definite necessity if one is going to achieve success.
Finding a good job, finding love, raising a family, being elected to high office...any of these things could be enough for someone to say that they have achieved success. Yet, for some people accepting these achievements as the definitive measure of success will be difficult. There is an urge for more. There is a doubt that what is in hand in enough. There is an internal need for greater outward acquisition.
So, being able to accept one's present state is potentially very important to achieving a real sense of success. Since success is subjective in nature, the "subject" has to be prepared to see it and embrace it.
I think that a large part of this question comes down to what one considers the meaning of life to be. I think that this is essential because in order to understand what are essential ingredients for success, one has to define what success is, and within this, one's overall frame of reference is revealed. All of these work together. With such a question, there are many points of view revealed. An enotes search on "meaning of life" reveals much in way of reference points. I think that the different schools of thought featured in such a search help to bring out many items that are essential "things" or ingredients for success. In the end, individuals have to determine for themselves what their end is, and what tools will allow them to achieve it. Certainly, knowledge is a part of this, almost a transcendent quality to all pursuits and also intrinsic to the desire or will to find success despite obstacles and challenges present.
This is indeed a question to which there are no simple answers. Great thinkers, and leaders have grappled with question like these for thousands of years without being able to come with any clear and definitive answers. What ever answers that are claimed to be definitive are firm subjective beliefs rather than objective realities. Such belief may have been identified by great spiritual leaders like the Christ and Buddha, and therefore highly credible. Still these are just beliefs and not objectively verifiable facts.
The problem in answering this questions are many. To begin with there is no common agreement on what constitutes success. Is an average king of a big country necessarily more successful than the humble cobbler who has never stitched a single defective pair of shoes in his entire life.
Some people suggest that happiness is the true measure of success. But happiness itself is not so easy to define or compare. Does a highly successful and happy executive become less successful when he faces a bereavement because of powers beyond his or her control.
When we cannot define what is success than how can we identify the things essential to success. To complicate the matter the further, there are very convincing arguments to support the philosophy that true success and happiness is in trying your best, rather than in achieving what you are trying. This amounts to say that the greatest success is not in succeeding but in only acting in the right spirit. As a matter of fact, I consider this kind of thinking a quite promising route to success and happiness in life.
Commenting on knowledge as one of the factors influencing success, I will say that knowledge definitely contributes to achievement of success in any field. But knowledge is also of many different types, and when some specific knowledge is applied inappropriately, it can also lead to failure.