Only when you constantly live as though already a corpse (jōjū shinimi) will you be able to find freedom in the martial Way, and fulfill your duties without fault throughout your life.

Only when you constantly live as though already a corpse (jōjū shinimi) will you be able to find freedom in the martial Way, and fulfill your duties without fault throughout your life.” (1-2) In other words, adherents of bushido should seek to nurture an indomitable fighting spirit free from concerns of life and death.

Meditation on inevitable death should be performed daily. Every day when one’s body and mind are at peace, one should meditate upon being ripped apart by arrows, rifles, spears and swords, being carried away by surging waves, being thrown into the midst of a great fire, being struck by lightning, being shaken to death by a great earthquake, falling from thousand-foot cliffs, dying of disease or committing seppuku at the death of one’s master. And every day without fail one should consider himself as dead

This is the substance of the Way of the Samurai: if by setting one's heart right every morning and evening, one is able to live as though his body were already dead, he gains freedom in the Way.
his whole life will be without blame, and he will succeed in his calling.

From the beginning of the year to the end, day and night, morning and evening, in action and repose, in speech and in silence, the warrior must keep death constantly before him and have ever in mind that the one death [which he has to give] should not be suffered in vain. In other words [he must have perfect control over his own death] just as if he were holding an intemperate steed in rein. Only he who truly keeps death in mind this way can understand what is meant by [Yamaga Soko's maxim of] "preparedness."

Being prepared to die is one of the great secrets of living.

Remember where you came from, where you’re going, and why you created the mess you got yourself into in the first place. You're going to die a horrible death, remember. It's all good training, and you'll enjoy it more if you keep the facts in mind. Take your dying with some seriousness, however. Laughing on the way to your execution is not generally understood by less-advanced life-forms, and they'll call you crazy.

You have to practice until you die.

Meditation on inevitable death should be performed daily.
Every day when one’s body and mind are at peace, one should
meditate upon being ripped apart by arrows, rifles, spears and
swords, being carried away by surging waves, being thrown into
the midst of a great fire, being struck by lightning, being shaken
to death by a great earthquake, falling from thousand-foot cliffs,
dying of disease or committing seppuku at the death of one’s
master. And every day without fail one should consider himself
as dead.

It’s important to cultivate detachment. One way to do this is to practice imagining yourself dead, or in the process of dying. If there’s a window, you must imagine your body falling out the window. If there’s a knife, you must imagine the knife piercing your skin. If there’s a train coming, you must imagine your torso flattened under its wheels. These exercises are necessary to achieving the proper distance. The motive is paramount. Without a strong motive, you’re sunk. My motives were weak: an American-history paper I didn’t want to write and the question I’d asked months earlier, Why not kill myself? Dead, I wouldn’t have to write the paper. Nor would I have to keep debating the question.

Everybody knows they’re going to die, but nobody believes it. If we did, we would do things differently,’ Morrie said. ‘So we kid ourselves about death,’ I (Mitch) said. ‘Yes, but there’s a better approach. To know you’re going to die and be prepared for it at any time. That’s better. That way you can be actually be more involved in your life while you’re living. . . Every day, have a little bird on your shoulder that asks, ‘Is today the day? Am I ready? Am I doing all I need to do? Am I being the person I want to be?... The truth is, Mitch, once you learn how to die, you learn how to live… Most of us walk around as if we’re sleepwalking. We really don’t experience the world fully because we’re half asleep, doing things we automatically think we have to do… Learn how to die, and you learn how to live.

you should learn as if you were going to live forever, and live as if you were going to die tomorrow.

You're going to die a horrible death, remember. It's all good training, and you'll enjoy it more if you keep the facts in mind. Take your dying with some seriousness, however. Laughing on the way to your execution is not generally understood by less advanced lifeforms, and they'll call you crazy.

Most of life is just a preparation for getting ready to be dead for a very long period of time.