Many years ago, I broke my leg two months before my 2 kyu test. I was in a walking cast and found that I could practice. Not only could I practice, I found that I learned a tremendous amount. Since I could no longer rely on the strength of my leg, I truly began to move from my center. Because of the cast, I stopped going up and down and began to truly move forward and backward. Additionally, since I tired very rapidly, I became more relaxed and softer. The cast came off two days before my test. I have never tested as well.
See also: Polishing the mirror and grinding the stone by Dennis Hooker.