What is your greatest physical challenge?

My vocal chords don't like to co-operate with me. I've had a stutter/speech impediment since I was 6. It got worse as I grew older, to the point of it being considered "very severe" by a speech language therapist. I'm doing a lot better now though, after a few years of speech therapy. Keeping it under control is an on going effort. It's annoying and it still gets in the way of everyday life frequently, but I'm just glad I can speak.