While performance skills are necessary and important, by themselves they do not guarantee success. You can work hard at what you do, but what about the things that lie behind what you do? The underlying ingredients, if you will. There are numerous "essential qualities", both physical and mental, which can contribute to optimum performance such as strength, reaction time, flexibility, endurance, coordination, power, etc.
The highest quality that any martial artist can possess is adaptability, to be able to adapt to any opponent and any situation. In any combative situation, there are numerous variables of combat that you do not get to dictate. The following are some of the prime variables:
• The size, weight, and body-type of the opponent -- tall and long-limbed, short and stocky, heavy, skinny, etc.
• The opponent’s mental or emotional state -- cool and calm, angry, nervous and agitated, etc.
• The relative speed, power and agility of the opponent
• What lead (if any) the opponent chooses to from -- right lead, left lead.
• What type of on-guard position the opponent is in -- open, closed, tight and compact, crouching, etc.
• What method or style of fighting the opponent will use -- martial arts, boxing, grappling, street-fighting, etc.
• The type(s) of attacks the opponent may try to use -- punching, kicking, elbows/knees, throwing, grappling, locking, etc.
• The type of fighter the opponent is -- runner, blocker, counter-fighter, crasher, etc.
• The number of opponents you have to face -- one, several, etc.
• The environment the situation takes place in -- city street, beach, woods, etc.
• Whether the opponent is unarmed or has a weapon.
While you may be able to influence one or more of the above variables, you don’t get to dictate them. So the goal of training in JKD is to know what you can do. Not what techniques you can do if you are attacked, but what you can do. Adaptability is the key. So develop your ability to adapt and fit in with an opponent and express yourself to the highest degree at any given moment and in any given position.