It it important to post on the correct diagonal so that you can more easily turn your horse and so that you’re weight is on the horses’ inside hind leg. The saying is “Rise and fall with the shoulder on the wall.”
The correct diagonal is important is because it puts your weight on the horse’s inside so it helps to engage your horse there, it also helps you influence the outside shoulder a little more helping your horse to turn.
To change you posting diagonal, you must do a down-down up or sit for 2 bounces in the saddle. Make sure not to lean off the side of your horse when checking your diagonal!
