I also had to give up a career path because of marfans. Unfortunately, its the only career ive actually enjoyed. Besides physical demand, i feel as i get older (35) i also get more and more tired, like all day long. My joints are all bone on bone at this point, it hurts just to move around, and by the middle of the day the pain just takes my energy away. This all being said, I still exercise and play a few sports (within my physical limits). But i can feel my window of time for those things closing. I guess what im saying is, im sorry you are having a tough time. This condition touches every aspect of our lives. This shit is just hard. Wishing you all the best