You and I face challenges that many people know nothing about. Do you think about how you should react and live? People are watching us go through the difficulties, troubles and heartbreaks. They may be observing you when you least expect it. It's an opportunity to live out the life of Jesus in this crazy world. People need to see that Jesus is real - He's life changing! His thoughts and words are radical.
So getting back to my first thought - use this body that you have and use the circumstances you are in to be an example to the world of Jesus Christ here among men. Remember that people look at you, Christian, and form their opinion of Jesus Christ. He has equipped us to live godly lives in this world, so remember that "God has not given us a spirit of timidity, but of power and love and discipline" so that we might draw the world to Himself. It takes a courageous person to deal with Parkinson's Disease daily over a long period of time, but God has supplied you with the power and the love to live victoriously before the world. You WILL influence the world around you either for good or bad. Choose good!