The meaning of Mokuso 黙想 is Meditation. The first character Damaru 黙る, means to be silent. The second character Omou 想うmeans to think. Mokuso as one word is also translated as silent contemplation.
To contemplate is to think about something deeply or look at something very carefully and thoughtfully. Not just looking or thinking but really taking your time. The looking, thinking or pondering or whatever action is done silent though in this context.
There are different styles of meditation with different purposes. In Martial Arts context, meditation is usually done to attain Mushin - no mind.
In short, you have to be at ease with control over yourself. Breathing relaxed and naturally. Do not judge any thought that pops up in your mind.
Mokuso is the meditation that is part of the ceremony before and after karate practice. This meditation has its roots in the mushin-training from Zen-Buddhism. It is also part of the mental training of karate.
The goal of mokuso is to attain a state of mushin, literally translated ‘no mind’. This means a state in which someone is not affected by emotions such as fear for hunger, thirst, cold, pain etc. You have to find the peace in your body and mind. After intensive practise you will approach every situation fully natural, calm and spontaneous, even a fight.
One who focuses on a pretty flower, is usually only aware of the flower. One who focuses primarily on defence, limits oneself to defensive technique. With an open mind (and enough experience) the body is able to move automatically. Your movement will therefore be natural and relaxed. It is essential to move instinctively. Mokuso is a fundamental method in helping to achieve this.
According to Yokoyama Sensei, Heijoshin is what allows you to stay calm inside. It does not mean that you do not have emotion. It is about not being consumed by that emotion.
In case of win or loss, are you able to show the same expression?
In case of trouble, the natural reaction is to become afraid, freeze or run away because of the fear. Another response is to become violent and aggressive (Freeze - Fight - Flight response).
Heijoshin is the natural state of mind that allows you not to be drawn to either being consumed by fear or aggression.
Heijoshin is commonly translated as tranquil mind.
Other words in English that match the meaning are peaceful or calm mind. It is interesting to learn that the Kanji for Hei Jo both refer to neutral.
In old books of Ishikawa sensei it is written that you can deal with trouble with a calm and relaxed mind. From my personal experience I can say that everything can happen in a split second, there is no time to think. Your body has to act subconsciously on its own, but at the same time you have to be in control and act proportionally according to circumstance.
Zanshin is made by two characters of Noko (pronouced Zan) and Kokoro (pronouced Shin).
Noko means remainder or leftover.
Kokoro means heart (not the organ), mind or spirit.
Zanshin is commonly translated as alertness. However, considering the individual meaning of both Kanji, it appears that Zanshin refers to the state of mind after engagement.
To progress in karate, you need a malleable mind.
For example, someone can train and work hard on his technique and/or his mental attitude, but he has to remain very critical to himself and also he has to accept criticism from others (for example the teacher or more experienced students). Only he who keeps his eyes opened for what he is not doing well enough can make changes in his movement and progress.