I know Jiu Jitsu.
Back when I was at undergraduate University I really wanted to learn a martial art. I'm not a warrior-type (ksatriya), but I fantasized about being physically powerful. I enthusiastically read up about all kinds of different styles, comparing their advantages and disadvantages, analyzing which was the most powerful, deciding on which to practice. In the end, I concluded that Jiu Jitsu (literally: soft technique) was the best (most lethal) and joined the local university club. I practiced it for four years.
The training involved various throwing, locking and grappling techniques (with a little bit of punching and kicking). For example: I recall nine different ways how to break someone??(TM)s arm, six different ways to break their neck, that kind of thing.
Gradings were intense affairs designed to mimic the high-stress situation of a real life-or-death struggle. Students would first be tired out by physically exhausting technique demonstrations and then put into a situation where they would have to defend against a continuous stream of attackers.
I gradually learnt to be fearless, to keep my cool no matter what the situation and to just keep going, regardless of any pain or exhaustion. Always keep on fighting! Never give up!
Advanced material artists have some realization that they are not the body. Once the body and mind have sufficiently learnt the techniques, they can run on auto-pilot. Fighting becomes automatic. It is a state of meditation. We are not the doer, the outcome is outside of our control; all we have to do is continue trying to execute our duty (note BG 2.47).
Indeed, the samurai warriors of ancient Japan understood this. They knew their fate was pre-determined. They did not care whether they lived or died. They were completely detached.
The way of the warrior (Bushido) teaches this kind of detachment. However, it offers no positive alternative. Once you??(TM)re detached from the body and mind, then what do you do?
The training was gradually taking its toll on my body: continuously bumps, bruises, strained muscles, sore joints, etc. Additionally, as I practiced more and more Krishna consciousness I gradually lost interest in mastering the physical body. There was (and still is) much more pleasure and satisfaction to be had from mantra meditation. It offers attachment to Krishna, while simultaneously detaching me from the body and mind. That is real knowledge!
Nevertheless, I??(TM)m happy I practiced Jiu Jitsu while I did. I??(TM)m pretty rusty now, of course, but certainly more confident and able to hold my own in a fight. I also understand more than ever before that I??(TM)m not the body and not the mind. The soul is where it's at.