Morality means choice. Choice means priorities. Priorities mean a hierarchy. A hierarchy means something at the top, a standard. That is the greatest good. If you have no greatest good, you have no hierarchy, you have no priorities. If you have no priorities, you cannot make intelligent choices. If you cannot make intelligent moral choices, you have no morality. You can still guide your life by your feelings or by social fashions, but that is not choice – not free, responsible, moral choice. Both feelings and fashions push you; you are passive. But moral choice is your own doing; you are active. You are responsible for your choices but not for your feelings or for your environment’s fashions.
I have no choice about whether or not I have Parkinson's. I have nothing but choices about how I react to it. In those choices, there's freedom to do a lot of things in areas that I wouldn't have otherwise found myself in.