“What I might have had” is grounded in what I expect of my future. Usually, I measure my expectations in comparison to other people but, as Heidegger pointed out, this causes me to become lost to the crowd (or the “They”). Other people are separate to me and as such have unique experiences and instances of thrownness, including their prognoses. Therefore, mourning expectations founded in comparison to other people essentially unlike me is empty. The only entity that I can intelligibly be compared to would be a person with the same experiences and thrownness as myself; I am that person! I must be compared to myself in my current possibilities; my past possibilities have already been used up and possibilities in my future have yet to be discovered.
My current possibilities have to surrender to the limits of my thrownness, which includes Parkinson’s. Therefore, mourning what I might have had ignores my thrownness completely. Further, applying to myself a prognosis based on other people tries to cover up the blindness I have of my future possibilities. I can only compare myself to my current possibilities and judge what possibilities I am currently choosing.
Therefore, my prognosis is not part of my “now” since it is something unknown in the future.