In Jeet Kune-Do, physical conditioning is a must for all martial artists. If you are not physically fit, you have no business doing any hard sparring. To me, the best exercise for this is running. Running is so important that you should keep it up during your lifetime. What time of the day you run is not important as long as you run. In the beginning you should jog easily and then gradually increase the distance and tempo, and finally include sprints to develop your 'wind.' Let me give you a bit of warning: just because you get very good at your training it should not go to your head that you are an expert. Remember, actual sparring is the ultimate, and the training is only a means toward this. Besides running, one should also do exercises for the stomach — sit-ups, leg raises, etc. Too often one of those big-belly masters will tell you that his internal power has sunk to his stomach; he's not kidding, it is sunk and gone! To put it bluntly, he is nothing but fat and ugly.

To me totality is very important in sparring. Many styles claim this totality. They say that they can cope with all types of attacks; that their structures cover all the possible lines and angles, and are capable of retaliation from all angles and lines. If this is true, then how did all the different styles come about? If they are in totality, why do some use only the straight lines, others the round lines, some only kicks, and why do still others who want to be different just flap and flick their hands? To me a system that clings to one small aspect of combat is actually in bondage.

The first rule is to keep yourself well covered at all times and never leave yourself open while sparring around the bag. By all means use your footwork — side stepping, feinting, varying your kicks and blows to the bag. Do not shove or flick at it. Explode through it and remember that the power of the kick and punch comes from the correct contact at the right spot and at the right moment with the body in perfect position; not, as many people think, from the vigor with which the kicks or blows are delivered.

The combatant should be alive in sparring, throwing punches and kicks from all angles, and should not be a co-operative robot. Like water, sparring should be formless. Pour water into a cup, it becomes part of the cup. Pour it into a bottle; it becomes part of the bottle. Try to kick or punch it, it is resilient; clutch it and it will yield without hesitation. In fact, it will escape as pressure is being applied to it.

To develop proper distance and penetration against a moving target, use a partner equipped either with a body protector or an air bag. He can either stand still and take the brunt of the kick, or he can back away from the attack. The former teaches proper application of the kick, especially valuable in teaching beginners. The latter training is to teach penetration. As soon as your partner thinks you will attack, he tries to back away as fast as possible. This practice is valuable to both men; one learns to penetrate and the other to back away quickly. The body protector is sometimes used for sharpening the attack. The partner will not attack but will maintain a correct distance in a ready fighting pose. As you begin to attack, he will try to counter, block, or move away. You will have almost the actual feeling of hitting your opponent in a real situation.