Zanshin and Mushin
Karate techniques should persist within the minds of those who witness them. When anyone does something truly remarkable, there is always a moment of stunned silence right before someone shouts “Whoa!” or “Dude! That was awesome!” That stunned silence is zanshin (literally: "lingering mind") and all inner peace and self-actualization is found within that moment. Also, this moment can serve as an atemi to those who share in it.
Achieving zanshin requires constant practice under stressful conditions, until attacks are met with an icy, jaded attitude instead of reacting out of fear. This is why we require mandatory sparring for every student, at the end of every class. It is imperative for this icy, confident, and professional attitude to linger after a technique completes. Zanshin is the only defense against becoming lost in the moment, or succumbing to the thrill of danger. These are crucial, since you must remain completely aware of your surroundings to ensure that you are mentally and physically ready to defend yourself again, if needed. As such, zanshin precludes all thoughts of celebrating victory, or turning your back on a fallen opponent. Success requires maintaining the same level of focus throughout all phases of a technique's execution. It's much like target shooting; if you flinch when squeezing the trigger, then you will miss.
Applying zanshin to all aspects of your training and daily life gradually cultivates mushin (literally: “no mind”), a state-of-being characterized by an endless flow state. Mushin is not "autopilot," or a zombie-like brainlessness. Mushin is a focused mind which has been freed of all distractions, clutter, unproductive emotions, and self-imposed limitations. Mushin is a freedom from definitions.