From the Wikipedia article on Jujutsu:
"The Japanese have characterised states of mind that a warrior should be able to adopt in combat to facilitate victory. These include: an all-encompassing awareness, zanshin (literally 'remaining spirit'), in which the practitioner is ready for anything, at any time; the spontaneity of mushin (literally 'no mind') which allows immediate action without conscious thought; and a state of equanimity or imperturbability known as fudoshin (literally 'immovable mind')."
With regards to anshin and mushin, I've done some significant work in my life. Being ready for anything at any time is applicable to improvisation, stage combat, temping, not to mention simply trying to get acting jobs. Spontaneity, the release of conscious thought, is harder for me but a life in the theatre naturally keeps me in reasonable form. Fudoshin, if I understand it correctly, is one in which I have to date been sadly lacking. I'll try not to judge myself here -- "sadly," it may not be; but "lacking," certainly. For most of my life I've regarded such a quality to be ultimately negative, relating it to stubbornness or narrow-mindedness. As I embrace my adult life, however, I begin to see that it is not only a desirable quality in many cases, but a necessary one, in some.
Of course, the Japanese express the idea more beautifully than I could ever hope to:
"A spirit of unshakable calm and determination,
courage without recklessness,
rooted stability in both mental and physical realms.
Like a willow tree,
powerful roots deep in the ground
and a soft, yielding resistance against
the winds that blow through it."
So how do we cultivate this quality, this ability, this eventual instinct in our lives? That's one of the things I'm aiming to find out.