How do I get a horse to respect my space on the ground?

A horse that crowds, pushes, or walks over the handler is not being affectionate — it is testing boundaries in the same way it tests other horses in a herd, and a handler who tolerates it is teaching the horse that its size and weight are tools that work. Establishing personal space starts with being clear about where your boundary is and enforcing it consistently every single time, not most of the time. Decide that a zone of roughly an arm's length around your body is yours, and that the horse does not enter it without being invited. When the horse steps into that zone uninvited, move it out immediately with a firm bump of the lead rope, a swing of the rope end toward the shoulder, or direct pressure on the nose or shoulder — whatever it takes to move the feet, applied without anger but without hesitation. The correction needs to be immediate and consistent to be effective. A correction that comes three seconds after the invasion teaches the horse nothing useful. Equally important is what you do not do: do not step back when the horse steps toward you, because retreating teaches the horse that advancing works. Hold your ground, move the horse out, then release and be neutral. Horses that crowd are often testing whether you are a leader worth following — consistent, calm enforcement of your space answers that question clearly. Within a few sessions of honest enforcement, most horses stop testing the boundary because it reliably does not move.