Soft, sympathetic hands are easy to apply from a correct seat or half-seat, supported by strong legs. While, in due course, a car can be fitted with new brakes, a new mouth for a pony is unobtainable.
By keeping your left hand low, neck-reinning becomes extra effective for all lateral adjustments. The use of strong legs, before slowing or stopping, will lessen the amount of contact on the mouth by the hand. Halting can also be assisted by looking behind you, because it gives the pony a better and more pleseant warning than a pull in the mouth.