For every jumping fault a horse may have, there are specific exercises that can be used to improve it. But there are a few exercises that will improve and sharpen up nearly every horse. And this is one of the best!
"In every sport, life goes in waves, up and down, keep rowing the boat and you’ll meet the next wave coming up, but don’t jump out of the boat!" ~ Chris Bartle
To make your seat stronger when seated in the saddle, think of using your core muscles in a downward fashion.
Horses need to be honestly connected and on the aids before they can stretch properly over their entire topline. Without that connection from behind, the stretch will be the horse's neck only, which is far less productive than a real stretch over the back.
In the sport of Eventing, ensuring that our horses are truly fit for our level of competition is one of the best ways to prevent unnecessary injuries.