Welcome ursus. Have you ever heard of Steven K. Hayes? He studied Ninjutsu in Japan as a young man. He has a training center here in Dayton, OH. I find his books very interesting and instructive. It's hard to put some of his stuff in to practice when you have a spinal defect though.
"Beloved let us tolerate one another. For tolerance is of God and everyone that tolerates is born of God and knows God. He that tolerates not, knows not God for God is tolerance." 1 John 4:7,8