Think about the last time you were with your horse. How many times did you ask him to halt while working with him on the ground? Before you mounted up?
When interacting and working with our horses, so much of it happens on the ground. Beside your horse.
In fact, all conversations with your horse start and end on the ground. Before you mount up and when you dismount after each ride. So it makes sense to use this daily interaction to intentionally help your riding.