Instructions
Relax your whole body, but especially your hips. Keep your hips open and flexible. You want to isolate your hips so that they're following, with a back-and-forth "sweeping" motion, the horse's movements.
Find the even rhythm of the horse and move with it. Focus on being one with the horse.
Work on your core strength. This will help with stamina, and will keep you from hunching over as you ride the lope.
Keep your body vertical; don't lean forward. If you get tossed forward when the horse begins the lope, grab onto the cantle (the back of the saddle) to steady yourself.
Anchor your heels and legs at the horse's side. The balls of your feet should be in the stirrups, and your heels should be pushed down to steady you. Try not to bring your legs up and squeeze to steady yourself.
Roll your hips back if the horse speeds up, and pull lightly on the reins. A well-trained horse will take these cues and will slow down.
How to Keep My Seat While Loping
Of all the Western gaits to ride to, loping can be the most exciting. It's a three-beat rolling motion, much smoother than the jog; the horse's feet come off the ground for a second with each stride, giving the rider the sensation of flying. For a new rider, a loping horse can feel out of control. Keeping your seat is important for feeling secure while riding at a lope.