Instructions
Ask your horse to canter in a large circle. Eventually you will be able to put your horse on the bit in a straight line, but in the beginning a circle will help control speed.
Take up the reins with both hands until you can just feel your horse's mouth. Use both hands at this stage whether you ride English or Western. Once you know the feel of a horse on the bit and your horse is familiar with what you are asking, you will easily be able to change to using just one hand.
Squeeze with your legs and seat as you open and close your fingers on the reins like you are squeezing a sponge. This will encourage the horse to soften its mouth and encourage reaching for the bit.
Continue squeezing with your legs as you use the reins to contain forward motion. You will know your horse is collected when it feels as though it's capable of doing almost anything --- changing direction, switching leads, speeding up or slowing down --- in the next stride. At this stage, it may be helpful to keep your inside leg pressed on the horse while tapping your horse lightly with your outside leg as the hind leg comes forward. Pressing with your inside leg will help keep your horse upright and will prevent him from leaning into the circle or "dropping the shoulder" in horseman's terms.
Continue riding with your horse on the bit. Reverse cues when you travel in the opposite direction. Keep your horse on the bit while you try your horse at other speeds.
How to Train the Horse on the Bit in Canter
A horse on the bit has a long, flowing stride and carries more weight on the hind quarters where the most power is located. The horse's neck will be lowered and the face will be more vertical. The horse will not be pulling on the rider's hands, but will actively seek contact with them. A horse that is on the bit and collected will be easy to ride and capable of performing a variety of advanced maneuvers. While it may be easier to put some horses on the bit because of their conformation, any horse can achieve collection with practice.