When I was a kid, my knickname from my father was smiley, because I always had a smile on my face.  I either was happy all of the time, or it was like I knew the punchline of a joke all of the time.  I have kept that optimism even now.  It is a lot harder now with the MS of course, but this is where you can either sink or swim.  I try not to focus on the things I can't do, but every move is an acomplishment.  I hate stairs, but when I am at the top, I think, wow, I did that and I am glad it is done.  I remember a delivery job that I had, before I was diagnosed, and I used to think when the order was droped off, "next".  That is true zen.  I remember a story that someone told me a long time ago about how the zen pupils would be beaten with bambu sticks by the zen masters to make you think of right now.  Don't obsess about the way things are, just think about the task at hand ,which is sometimes how you are going to get to the bathroom, and just do that.  Zen means now, right now.  Not five minutes ago or five minutes from now, right now.  That is all that exists and matters is right now.
I have got a good story from years ago that is not very zen.  A long time ago, I was driving in my car and debating about doing something, actually, I was deciding if I wanted to drop some acid, a storm was brewing in the sky and the song on the radio was the Van Halen song "Right Now".  When Sammy Hagar said, "right now", a flash of lightning lit up the sky.  How can you ignore a sign like that?  Live your life right now, because there are worse things than this ataxia that I have from MS.
I hope you are not offended by the LSD story, but it happened.