side of the horse. as the horse starts to move, relax the pressure of your legs. if your horse does not respond, you can give a gentle kick into his side while making a clucking sound with your tongue.
your horse can be thrown off balance when you go up or down a hill so you will need to adjust the way you sit in the saddle. when going downhill, you need to lean back in the seat, and you need to lean forward when you are going uphill.
a majority of trail horses are trained to neck rein. this means you hold both reins in one hand. then when you want 