What joy do you get while working?
Many people say that after finally getting what I want, I will get a great excitement and joy.
It is true. But in thinking so what you are doing now becomes a means toward this excitement. This can give you a good motive to work. But after a while you will come to want that great excitement and joy without working hard, because your working is just a means, not fun itself. It gradually becomes painful.
So we have to find joy in what we are doing now, not in an achievement. What you are now is what you have been doing thus far.