From my own experience I can say that a bad back makes you hike slower, stove-up knees keep you from wading confidently, tendinitis of the elbows buggers your casting, and a dose of giardia can send you dashing to the bushes fifteen times in an afternoon, but although none of this is fun, it's discernibly better than not fishing.
John GierachI like to do every operation the same way on each fly. In the course of tying a batch of flies, I might get an idea on how to do something differently, but try to save it to try out later rather than break my comfortable rhythm. I don't worry about forgetting it. In my experience good ideas stay with you, while bad ones go back to where they came from, and good riddance.
John GierachThe best fisherman I know try not to make the same mistakes over and over again; instead they strive to make new and interesting mistakes and to remember what they learned from them.
John Gierach