This is an excerpt from Gentle Art of Horseback Riding, The by Gincy Self Bucklin.
The Sitting Trot or Jog
Up to now, if you have been following the program, you have always had someone nearby who was guiding and controlling the horse so that you could focus on developing balance and grounding. The next step is to ride by yourself in a confined space large enough for the horse to move around in comfortably but not so large that he is able to do anything that you aren't ready to deal with.
You still won't be using the reins, but you will use your gentle aids to help to guide him and keep him going. You can use your emergency dismount in case something comes up that makes you uncomfortable. But you still need one more skill: to be comfortable at a slow trot. To practice your skills, you have to keep the horse moving. If you get a little too enthusiastic with your stick, he will probably break into a trot, so you should be prepared.
In English riding the gait you will work at is called a slow trot, and you will learn to sit to it. In Western riding the same gait is called a jog, and sitting it is the way it is usually done. There are several ways to ride the trot, all of which you will be learning later on in the book, but I have found that this is the easiest way to start.
Notice that in English riding it is called sitting trot, not bouncing trot. This is an important difference because if your seat leaves the horse's back and then comes down again, it can be quite painful for him, especially if prolonged. Try this little exercise to give you an idea of how sitting feels to the horse compared to bouncing.
Sitting Versus Bouncing Exercise
Hold your forearm out and pretend it's the horse's back, moving up and down. Make a fist with your other hand and place it on the middle of your forearm. Just let it lie there of its own weight while you move your arm up and down. You can move your arm faster or up and down more, but as long as your hand lies steady on your arm so it follows the movement, there is no discomfort.
Now continue the movement of your forearm, but hold your fist still so it doesn't follow the movement. Instead, it will bang against your arm, which is annoying and eventually uncomfortable. You can imagine what the weight of a full-grown adult bouncing on the horse's back would feel like!
Preparatory Ground Work
If you have access to a small trampoline, you can get a really good feeling for riding the trot. Keep in mind that the gaits are already programmed in your body. The bounce of the trampoline, while not essential, gives excellent feedback, similar to what you will get from the horse. You will need something to hold on to while you're on the trampoline to help you ground. A piece of rope tied to a heavy chair leg will work.
Whether you are on the ground or the trampoline, begin with the seven steps. Then start walking in place, feeling the rhythm and how your body moves and interacts with the floor or the trampoline. Try to put your feet down very softly, which means keeping all your joints, starting with your spine, very loose.
After a few minutes, begin to jog slowly in place, trying to keep the same soft, flexible feeling throughout your body, and hitting the ground as softly as you can. Notice that even though you aren't going high or fast, the jog is still much bouncier than the walk. This is true of the horse's gait as well. Jog for a while, then walk a few steps, then jog again. Think about how your body moves differently at the different gaits.
Riding at the Slow Trot (Jog)
You are still using your leader and will need her for this task so that she can control the horse's speed and gait while you are learning to sit. Begin the exercise after you are well settled on the horse. You might find it helpful if an experienced rider demonstrates sitting the trot first so you get an idea of how it should look. Notice how she uses the grounding strap and how her seat doesn't leave the horse's back at all.
Prepare for the trot by using the seven steps and the grounding strap to get relaxed and grounded. Growing and shaking out are particularly important steps as you prepare for the trot. The additional bounce must be absorbed by your inner thighs and buttocks, which must be very soft and relaxed, and by your lumbar spine, the flexible part of your back at your waist, between your rib cage and your pelvis (figure 11.10). The shake-out will help to loosen up the muscles, and growing will stretch and loosen the spine. You will also need a slightly stronger feel on the grounding strap to counteract the bigger movement, so practice taking that stronger feel without creating any tension in the areas of your body that contact the horse.
Having the horse walk over rails on the ground, if available, or down a slight grade will make his walk a bit springier and prepare you for the new movement.
When you're ready, the leader can ask the horse to trot. If she starts jogging slowly herself, keeping her body grounded and landing softly, the horse will tend to copy her, making the gait smoother for you. As the horse starts to trot, allow your body to sway back a little (figure 11.11); leaning very slightly back during the trot makes it easier to sit. Then think about breathing, maintaining soft eyes, and your following seat. Use your grounding strap to keep you down on the horse's back, but don't pull on it so hard that you make yourself tense, which would defeat the purpose.
The first time you attempt this, the leader should trot the horse for only a few steps, just to give you the feeling. After that, if things go well, the trots can get longer but should be confined to straight lines at first so you don't have to deal with lateral centering. You can continue to trot each time as long as you are sitting comfortably, but if you start to lose the feeling and can't regain it right away, have the leader bring the horse back to the walk, reground, and start again.
Once you are comfortable on the straightaway, try some gentle turns. Even though the horse is going only a little faster, the livelier movement tends to make staying in the center more difficult. Practice at the walk, making a tight turn and using a strong lift and weight shift to keep you centered. This will be less effort at the trot because the horse will lift you up. Keep the turns fairly brief at first, beginning with left turns as you did at the walk. Once you have the knack, try some longer turns. Also work on sharper turns, since you will be riding by yourself in a fairly small space.
Finally, try an emergency dismount from the trot. The leader should start you at a slow jog that you can sit to easily, then speed up the trot just enough so that sitting becomes more difficult, at which point you should dismount. By now you should be well versed in turning, facing forward, and landing softly and safely with toes relaxed and knees and ankles bent. You will find it much easier to get your right leg over because the motion of the trot will be lifting you up. The leader should stay well in front of the horse so you don't bump into her.
What might surprise you is how quickly the horse stops as he feels your center coming forward in front of him. I used to bet my students that they couldn't get to the ground before the horse had stopped. I usually won.
Read more from The Gentle Art of Horseback Riding by Gincy Self Bucklin.