For me, that quotation means that, even if you're doing what you need to be done, will still not make you happy because sometimes for you, it is not that important for you to do, but it will make you great, because when you finished something (that is needed) you cannot stop to feel that way like "At last! I finished it! I have nothing to do anymore. I can now watch TV". Means, you're feeling great because you have nothing to do anymore. Just like, when you do your assignments and you already done it, you don't feel happy, but it makes you great because you can now do anything you want to do..
That's how I understand that quote. Pero parang may hindi ako ma-explain, para kasing double meaning eh.. Try mo ring intindihin para kung sakaling mali yung explanation ko, may sagot ka :)))