Jissen is not simply a matter of one person controlling another person. Both players have the same goal: hit the other dude without letting him hit you. At lower levels, it’s often enough to simply bully your opponent, subjecting him to your will. But a strong opponent won’t allow you to do this, and you’ll find that you must respond to his actions while you pursue your agenda.
To make a long explanation of the nature of jissen very short, we need to practice responding appropriately to outside stimuli.
Though we tend to take this aspect of practice for granted, communications science has demonstrated that many of the most challenging problems in any multi-person situation arise out of the inability to read signals accurately. (Incidentally, if you don't believe that fighting is a form of communication, you especially need to practice these next drills.) Sometimes, the problem is a lack of sensitivity; sometimes it is difficulty in distinguishing noise from information.
We will address both capacities with the following developmental drills, some of which you may recognize from childhood games.
Standing Push Drill
Both partners stand, facing each other and try to push the other off-balance. The only contact allowed is with the hands, and whichever partner first moves his feet or falls down is the loser.
Standing Pull Drill
You can also have the partners grasp each others' hands and attempt to pull the opponent from his position.
Back-to-Back Push Drill
Partners stand with their shoulders and hips touching and link arms at the elbows. Pushing against each other, they attempt to force each other out of a predefined area.
Seated Back-to-Back Push
Same as above, but the drill begins with the partners sitting on the floor.
Linked Sumo Drill
In this variation the partners stand, facing and grab each others' belts. They can push, lift, or reap their partner's legs. This is very similar to sumo, with the exception that both partners remain linked for the duration of the drill. If either partner steps out of bounds or touches any body part other than the feet to the floor, the match is over.
Partners grasp one hand and attempt to tag the other partner with their free hands. The target can be specified (knee and shoulder work very well) or free. Be sure to practice using both sides.
Linked Step Tag
Similar to the above drill, except partners attempt to step on each others' feet. Steps and jumps can be used to avoid "attack," and players can use their hands to help control their opponent's balance. Make sure to practice both sides.
Linked Step Sumo
Players link hands as above and attempt to force their opponents to the floor or out of bounds. Contact is allowed with the feet, up to knee-height for tripping, and players can use their liked hands to pull.
Free Step Sumo
The object of the drill is as above, but only foot-to-leg and hip-to-hip contact is allowed.
Any of the above drills can also be played with more than two partners, within a wider or narrower area, using blindfolds, on uneven terrain (use kicks mitts, punch bags, crash mats, people, etc. for obstacles), with time limits, while carrying a load (such as a partner), on one leg, on both knees, wet, naked... - whatever floats your boat, paddles your canoe, or sinks your battleship (though in all seriousness, topless variations could be very beneficial for the guys).
Just remember to hold the concept that these are games
being played to improve your jissen. Don't get too excited and get injured with this kind of practice. In a safe and friendly environment, the drills listed above and their variations can be extremely fun ways to build our abilities to "communicate" with our partners in jissen.
These drills are also great for warming up to practice kobo and jissen. Since they work skills that we don't practice in hokei or kihongi, it's important to return to them periodically. They can't be mastered, so if you approach them with a fun attitude, they never get stale.