It is quite important while sitting in a saddle to think about your body and how you are postured and breathing. You should first focus on your breathing and stomach muscles, similar to meditation. It is important to lift your ribs or hold your stomach in while breathing shallow breaths through your nose. In order for a horse to be in frame, they must do the same, they hold their stomach in, back up, breathing rhythmic thru their nose.
Concentrate on the muscles 3 inches below your belly button where your center of gravity is. Focus on moving up and down and not going forward so much. This strategy has a big effect on the horse and encourages lightness of the feet. This style of riding requires full leg contact keeping the horse collected while keeping the reins loose which means lightly working the reins constantly to keep from getting tight or heavy handed. This allows the horse’s feet to stay light.
Bill Cameron International Horsemanship 