One of the hardest things to come to terms with when you are diagnosed with a progressive disease is fear of the future. It can plague your every move and throw you into the future while you miss the present.
Fear is useful when you are faced with an immediate threat; it focuses your attention and prepares you to fight or flight; it is a mechanism for self preservation. However, with the evolution of self awareness and imagination fear began to turn inward and prepare us physiologically to fight or flight from the idea of fearful things; we react to fearful ideas perpetually because we cannot take flight from the idea of fear (we are tied to our self-awareness of the fear) and fighting it is fighting our self.
Fear doesn't change the nature of the external object we are fearful of; fear is just a thought and thoughts have a limited sphere of influence. This is even more applicable to abstract objects of thought. For example, fear of a Parkinson's future is fear of nothing actual except thought itself since the future is not real yet (and thoughts do not create the future).
A way out of this fear of nothing is to acknowledge thoughts can be replaced by other thoughts; the idea of fear can be challenged by other ideas. We have an extraordinary ability to create thoughts and this gives us immense power in understanding and dealing with the external world and the world of thought. We can carry out a similar analysis to the one I did just now: the idea of fear is fearful about nothing except itself and elicits a perpetual physiological response normally reserved for the instant of being threatened by things in the external world.Thoughts change and with it the idea of fear can change.
We can choose to live in a world of fear, which is really a world in our imagination or use thought to limit fear to the immediate experience of external objects that threaten and resist carrying fear beyond the object to objects of thought.