Not to be confused with the will to power.*
To have the will to excellence is to strive always to improve in at least some area, and to never be satisfied with “good enough” in that context. It might be possible to have a will to excellence in all areas of life, but I suspect that would make the will to excellence a burden, because no one has the resources to devote to improving at everything. But usually when the will to excellence manifests itself it is restricted to a specific task or discipline, and so here I will simply ignore the possibility of the will to excellence being harmful for that reason. Despite its simplicity I think that the will to excellence is one of the most admirable qualities a person can have.
Not everyone has the will to excellence, in fact I think that most people lack it. Even so the will to excellence is something that I think should be desired, and not just because it is called excellent. In general people with the will to excellence tend to contribute more to society than those without it do. This is because those without it simply do what they need to get by and no more, and thus their motivation to accomplish something is mostly external; they act only because of associated rewards or punishments. In contrast those with the will to excellence have an internal motivation, and so they are led to attempt things which society can’t properly motivate, like great art. Of course not everyone with the will to excellence actually succeeds in doing great things, but some of them do. And so, from the viewpoint of society, it would seem that we should encourage the will to excellence.
Now that just means that there will be some social pressures to have the will to excellence. Which may make it seem like having a will to excellence is equivalent to being exploited by society, as you would be giving more to society than it gives to you. I maintain that there are also personal benefits to the will to excellence that make it worth having, even if society isn’t structured to reward people who have it properly. One reason to pursue the will to excellence is that having it makes it easier to feel that your life is well lived. I wouldn’t claim that it is required for a life to be well lived, but psychologically the feeling that you are getting better and better at something, and hence the feeling that you are accomplishing something, is a powerful one. And that in turn means that fewer distractions from life are required, making it easier in turn to follow the will to excellence. The will to excellence also has a number of beneficial side effects. Trying to improve yourself requires the ability to think originally, at least eventually, when you “catch up” to the state of the art in whatever your will to excellence is focused on. Similarly being driven by the will to excellence brings with it increased originality and a willingness to stand out from the crowd (since by being better than average at something is already to stand out).
But if the will to excellence is so good then why doesn’t everyone have it? One possibility is that most people just don’t have the capacity for a will to excellence. I think, however, that is an overly pessimistic view of human nature (but really there is no way to tell for sure). Another possibility is that the strong desire to conform to social norms prevents people from developing the will to excellence. Developing the will to excellence means being different from everyone who lacks the will, and it means being different from most of the people with it as well, since they are focused on something different. But I think the strongest factor preventing people from developing the will to excellence is simply that society seems not to encourage it. Society rewards the lucky, but not necessarily those with an inner drive, even when they do manage to accomplish something great. But it remains somewhat of a mystery as to why society doesn’t encourage the will to excellence, given that I established above that we should expect some social pressures in its favor. If I had to guess I would blame democracy. Democracy is based on the principle that everyone is of equal importance. Which means that it discourages thinking of some people as better than others (except when they have more money). Since the will to excellence is not usually rewarded financially society would have to reward people with it by recognizing them as better for having it. But that contradicts the democratic ideal, and so the will to excellence seems to go mostly unrewarded, and hence mostly unmotivated.
* Although you might be led to confuse it with the will to power, partly because Nietzsche can be vague about exactly what the will to power is. In a generous reading of Nietzsche the will to power is primarily a form of self-control, which might seem to overlap in part with self-improvement, as some form of self-control is necessary for self-improvement. However, the will to power is supposed to be present in everyone, which is not the case with the will to excellence. And, more importantly, it is not clear that the will to power really is an ideal. Certainly Nietzsche uses language that would lead us to believe that the will to power is something to be celebrated, but I think that whether that is actually the case receives too little critical attention.