Welcome to Marrowforums. I'm glad you've found us. There are lots of people here who can understand how you're feeling because many of us, including me, have had the same experience of being diagnosed with MDS.
You sound like you do have a very active life and you certainly don't want to lose that. For me, information was the key to keeping everything in perspective. The more I learned about MDS, the better equipped I felt to participate in the plan for my treatment and to manage my expectations for how much I could do in a given day.
Have you been in touch with the Aplastic Anemia & MDS International Foundation
? Be sure to get their basic information packet on MDS for a good overview. Then feel free to post about your fears and worries here. It helps to talk with people who understand what you're going through.