I have a young colt(gelding) that I have been doing natural horsemanship with since he was 9 months old. He is now 19 months old and I've introduced lunging for some exercise. Our sessions are very short, no more than 15 minutes at a time. I use a 15 foot rope with my rope halter. He never reaches the end of it though. He can walk, trot, canter both directions. Stops and stands until I cue him to go. He is perfect until I try to send him out a little further away from me. Its like once I try to push him out, we loose the connection. He'll just start to act up. He doesn't try to invade my space or anything. He just likes being close.
What are some ways I could go about getting him to move out?