Excellence does not mean perfection. Excellence means to strive to be at your best at everything you do. There is no limitation for you in what you should apply excellence, it helps you with work, family, hobbies, goals, etc.
It is also not related to how much you know, if you do the best with what you know, you are striving for excellence as well. And on the other hand, excellence is also related to keep learning more and more, so any lack of knowledge that you may have now, it will be solved as well if you keep up with excellence.
When you apply excellence to your life, it removes the guilt that perfection carries with it when, no matter what, you fail. There is no way that anybody can be 100% perfect every single day at every single thing that he or she does. It is just unrealistic to set goals that require perfection.
However, if the goals are based in be excellent, it takes in account that you are making the best with what you have at this particular moment, and when you grow/get better, then you will deliver better results. What excellent takes in account, is that at every single time you have to push of being your best self, if you don’t do, then you will not grow.
Achieving excellent results forces you to go out to your comfort zone, but not too much so the desired result is unrealistic. For example, if you want to start doing some sport, and you can only run for 5 minutes, getting to 5 minutes and 30 seconds is an excellent result.