When I was a little kid, my grandfather developed a neuron disorder that affected, not his normal walking stride, but specifically the neurons involved in starting to walk. Turns out it's a whole other set physics, and therefore a whole other circuit in your brain, that's responsible for getting all your momentum going from a standstill. Anyway, the result was that when he wanted to walk, say, from here to there, he would sometimes be beset by a shuffling, stutter-step motion as that circuit in his brain failed to compute. I can only begin to imagine how upsetting it must have been. It literally made him unable to move.

Grandpap lived very far away all my life and it was only once every several years that I saw him, so I didn't know him very well, and I also had never seen this problem in action, when I visited sometime in my 8th or 9th year. While he was taking us around his favorite aviation museum, he started doing a funny walk. He was kind of a grumpy old man and I was really happy to see him letting loose, and I laughed out loud. My Dad had to pull me aside and tell me not to laugh at Grandpap's neural disorder.