The following is an abridgment of Chapter 7: "Training Precepts" from Karate-Do Nyumon: The Master Introductory Text, by Gichin Funakoshi.
First, since karate is a martial art, you must practice with the utmost seriousness from the very beginning. This means going beyond being simply diligent or sincere in your training. In every step, in every movement of your hand, you must imagine yourself facing an opponent with a drawn sword. Each and every punch must be made with the power of your entire body behind it, with the feeling of destroying your opponent with a single blow. You must believe that if your punch fails, you will forfeit your own life. Thinking this, your mind and energy will be concentrated, and your spirit will express itself to the fullest. No matter how much time you devote to practice, no matter how many months and years pass, if your practice consists of no more than moving your arms and legs, you might as well be studying dance. You will never come to know the true meaning of karate.
Secondly, try to do exactly as you are taught without complaining or quibbling. Only those lacking in zeal and unwilling to face up to themselves resort to quibbling. Often their foolish complaints border on the pathetic. For example, in teaching the back stance, I come across people who say they simply are not able to learn the stance, no matter how hard they try. They ask me what they should do--after practicing for less than an hour! Even if one fervently practices the back stance every day, standing until one's legs become as hard as rock, it would still require six months to a year to learn it. It is ridiculous to say, "No matter how hard I try," without first working up a sweat.
You cannot train through words. You must learn through your body. Enduring pain and anguish as you strive to discipline and polish yourself, you must believe that if others can do it, you can do it too. Ask yourself, "What's stopping me? What am I doing wrong? Is something lacking in my approach?" This is training in the martial arts. Important points taught us by others may quickly be forgotten, but the essence of the knowledge acquired through personal hardship and suffering will never be forgotten.
Thirdly, when you are learning a new technique, practice it wholeheartedly until you truly understand it. Do not crave to know everything all at once. Practice painstakingly. Karate has many techniques and kata. Do not fall into the trap of thinking that because there is so much to learn, you should quickly learn everything in a general way. It would be quite impossible for an inexperienced person not knowing the meanings of the kata or the techniques contained in them to commit them all to memory. The kata would be nothing but an incoherent jumble of technique. Learning each movement and each technique independently, the student would fail to see how kata interrelate with kata and how kata integrate movements and techniques. Learning one thing, forgetting another, their final reward would be total confusion.
Fourthly, don't pretend to be a great master and don't try to show off your strength. It is absurd that many of those practicing the martial arts feel they must make a show of being a martial artist. Picture a man, shoulders raised high, elbows swinging, swaggering down the street as if he owned it, with a look on his face that says, "I'm the greatest hero that ever lived." Even if he were that, one's respect for him would drop by at least half. And, of course, if he was not a man of great ability but simply a synthetic hero, the situation would be too ridiculous for words. The tendency to act big or superior is usually most conspicuous among novices. By acting this way, they degrade and ruin the reputation of those seriously practicing martial arts. "Their smiles can win even the hearts of little children; their anger can make a tiger crouch in fear." This succinctly describes true martial artists.
A fifth point to remember is that you must always have a deep regard for courtesy, and you must be respectful and obedient toward your seniors. There is no martial art that does not stress the importance of courtesy and respectful manners. Courtesy and respect should not be confined to the dojo. Is there anyone who willingly follows the orders of their seniors in the dojo but completely ignores the words of their parents and older siblings? I hope not. If there is such a person, they have no right to practice a martial art.
Sixthly, you must ignore the bad and adopt the good. When you observe the practice of others and discover something that you should learn, try to master it without hesitation. If you see someone sliding into idleness, examine yourself with strict eyes. When you see someone who is particularly good at kicking, ask yourself why their kick is so good. How can you learn to kick like that; how does your kick differ? In this manner, you should be able to devise a method to improve your kick. When you see someone who does not seem to improve, again ask yourself why. Maybe they do not train enough or maybe they lack determination. Ask yourself, does not the same hold true for you?
This attitude does not apply only to improving one's technical abilities. We all have our good points and our shortcomings. If we are sincere in our desire to improve ourselves, everyone we meet can be a role model and a touchstone for self-reflection. An old proverb says, "When I walk along with two others, they may serve me as my teachers. I will select their good qualities and follow them, their bad qualities and avoid them."
Seventh, think of everyday life as karate training. Do not think of karate as belonging only to the dojo, nor only as a fighting method. The spirit of karate practice and the elements of training are applicable to each and every aspect of our daily lives. The spirit born of bearing down and gritting your teeth against the cold in winter training or blinking the sweat out of your eyes in summer training can serve you well in your work. And the body that has been forged in the kicks and blows of intense practice will not succumb to the trials of studying for a difficult exam or finishing an irksome task. One whose spirit and mental strength have been strengthened by sparring with a never-say-die attitude should find no challenge too great to handle. One who has undergone long years of physical pain and mental agony to learn one punch, one kick should be able to face any task, no matter how difficult, and carry it through to the end. A person like this can truly be said to have learned karate.