I stand up paddle surf, in the surf (ie, in waves, not flatwater), almost every day, for 2 hrs at a time, if not a little more. The Dr does not want me to do this, and I suspect I know why: at the end of those two hrs, I go straight to bed and/or mope around the house the rest of the day, too exhausted to move.
But, it's how I choose to deal with my disease. Surfing is what makes me happy -- and happy beyond words -- so why would I want to cut down on it, knowing that my disease is going to make me stop at some point anyway?
And, yes, there are times, usually at the end of the day, when my feet are burning to high hell and are prickly numb like no one's business and I swear that I'll take it easy and not surf the next day. But then the next day arrives, my feet seem somewhat better, so off I go, without fail, to catch waves.

(Here is a story I wrote about my case of CIDP and addiction to surfing: http://www.outsideonline.com/1922561...ithout-feeling )

One thing surfing has not done is increase my muscle mass. Due to CIDP, my leg muscles are almost entirely atrophied and my arms are skinny as toothpicks. That said, I have to feel that without surfing I might be even worse off than I am.

So, those are my thoughts, for what they're worth.