Are patterns a mental or physical exercise? I think they are more mental. Some people can perform a technically perfect pattern in class but cannot perform the pattern under stress, such as at a testing or tournament. Sometimes, I have students turn to face a side wall in the dojang and then perform their pattern again. Many students, even though they have correctly performed the pattern many times while facing the front of the class, get mentally confused when facing the new direction.

Some people whose physical ability may be lacking can still perform an beautiful and intense pattern that draws high scores. The body supports the brain, gives it mobility, and serves its will.

To prepare mentally, you must concentrate on visualization, attitude, and presentation. The old adage "What the mind can perceive, the body can achieve." is true. Visualize yourself performing each movement of the form perfectly every day and when the time comes to perform the pattern perfectly, the body will respond. Visualize yourself blocking and attacking a real opponent so you can appreciate the meaning of each technique. Practice relaxation techniques so you will be relaxed during the stress of pattern performance. Train with the proper attitude and you will perform with attitude. A pattern is a mock fight where you are defending yourself against attack. Have a warrior spirit. Perform the pattern with the same power and intensiveness that you would use in a real fight.

To prepare physically, concentrate on increasing your flexibility, strength, and endurance. These attributes will increase your power and speed and help you stay more relaxed during the physical exertion.

Physical aspects of patterns

It is physically taxing to perform a pattern the way its is supposed to be performed. Each movement should be precise with maximum effort. Each technique should be performed as if your life depended on it doing its job. The body is constantly tensing and relaxing. When you finish a pattern, you should be physically exhausted; you gave it everything you had. It would be impossible for you to immediately perform the pattern again with the same intensity. When you practice your patterns, you cannot maintain this level of exertion very long, so you back off some so that you may practice longer and perfect you movements.

Mental aspects of patterns

Students tend to overlook the mental aspects of patterns during their training, but they are just as, if not than more than, important. One of the obviously mental aspects of pattern performance is the kiai/kiyup. The kiai is not just a yell to be performed at specific points in a pattern, it is the convergence of all your energy and thought at a single instant of maximum power. When the pattern is performed correctly, you feel so good that you cannot help but make a noise. An explosion will make a loud noise, but a loud noise is not an explosion, likewise, the kiai is a shout, but a mere shout is not a kiai. When you perfect a technique to the point that you know an opponent would be powerless against it and you execute the technique in a pattern, you feel exalted at its perfection. This feeling of exaltation and perfection is released through the kiai. Only perfection will bring out a true kiai. Otherwise, it will only be a yell. If you have an unshakable belief in both yourself and your ability to apply the techniques of the kata, regardless of the circumstances, then your kata will posses kiai. 

When an opponent is helpless against your techniques, you will feel the kiai. When the opponent feels overcome by the kiai, he or she will feel "aiki." Aiki occurs when one is overwhelmed by a dominating spirit. Feeling aiki will cause an opponent to doubt his or her skills and to resign to defeat. In combat, if you break your opponent’s spirit so that they lose their will to fight, you are guaranteed victory. Sometimes a highly confident stare may cause aiki in an opponent. In the classic text, The art of War, Sun-Tzu states, “Achieving victory in every battle is not absolute perfection, neutralizing an adversary’s forces without battle is absolute perfection.” A high quality pattern performed to perfection will cause aiki in those who view it. They will feel a cold chill come over them. Arrogance, making mean faces, and overacting will not cause aiki. Aiki not a caused by a conscious effort of the performer,  is something that occurs naturally when one has perfected his or her pattern to point that it viewer are awestruck by it performance.

As you perform your pattern, you should look like an robot performing programmed motions. You should appear as a alert warrior who is reacting to attacks from unseen attackers. Your performance should cause viewers to visualize your attackers. They should feel as though they are watching a real fight. Master Itsou (founder of the pinan and heian karate katas), when outlining his philosophy of karate to the Prefecture Education department wrote, “During practice, you should imagine you are on the battlefield. When blocking and striking, you should make your eyes glare, drop the shoulders, and harden the body. Now block the enemy’s punch and strike! Always practice with this spirit so that, when on the real battlefield, you will naturally be prepared.” 

Once you bow at the beginning of the pattern, you should have "no mind," a mind that is open and not fixed upon any particular object or thought. You are not thinking about performing the pattern, you are merely reacting attackers with fearless power.

Do not exhibit arrogance during your performance. From the time you are called forward to perform you pattern, you should exhibit the quite courtesy and humility of a fearless warrior who has been called upon to do battle for the kingdom. A true warrior is confident and is to be feared, while at the same time presents him or herself as a kind, gentle and humble servant of the king.