Ninjutsu translates as techniques that allow for perseverance. This perseverance, in the broadest sense, is about persevering in life, never giving up. Failure only happens when we give up. Difficult states, feelings, and experiences can all make us want to give up.
Ninpo the deeper understanding of ninjutsu allows us to live from a place of 忍. This also translates as Shinobi, or one who lives, exists carrying the essence of, Ninpo. In order to do this we have to live allowing our heart (心) to be our guide. This is the foundational element of 忍. Soke tells us to focus on the feeling, live from the heart. To often we focus on completing the technique in the dojo and accomplishing the task(s) at hand in our lives without having any connection with our being. When we do this, we miss the kukan or potential for experiencing true Ninjutsu and Budo. The empty space is in the feeling. This is what guides true and solid technique with Shin Gi Tai Ichi. Start with heart as you focus on 刀. This is where life is found, expressed, and experienced.
At times this requires great mental and emotional effort to have the courage to acknowledge when we are in an unpleasant state, have uncomfortable feelings, and/or experience difficult things. Once we acknowledge this we can then begin to flow with it and journey through these moments where we can find the next best course of action. This may be an internal action or process, or it may need to be one that has a direct impact on your external world. Allowing our heart to be our guide towards courageous action, after leaning into the experiences we have acknowledged, we can then decide to have compassion toward what has happened, whether that is inside of us or what happened from outside of us. By doing this we can then access our Intuition to find a creative way to get back to a state of zero. Usually this process becomes in service to something greater than our own egos and what we want in a moment. This is Ten Chi Jin. Notice above how Chi, Sui, Ka, Fu, and Ku exist in this process.
Think of Fudoshin. Taking this journey each time we get knocked off balance and using our "ukemi" on all levels, physical, mental, spiritual is the path toward a settled and balanced spirit that is truly immovable not because we are unaffected, but because we trust we can always get back to zero even when we are "unbalanced".
Ponder this...
Ninpo Ik-kan!