I swear, it is the most amazing thing to see that lightbulb moment with a young horse. I didn't spend much time riding today because the wind is crazy, but I wanted to spend a few minutes on a couple and bump them up from a snaffle to a curb bridle. This one little mare I'm riding has been doing exceptionally well but wasn't quite able to put 2 and 2 together when it came to neck reining. She would do okay, but not as well as I would like. In ever other respect, she was completely ready for the bridle, she's soft, supple, and responsive so I figured I would give it a shot. It took her just a few minutes to get accustomed to the different pressure and direction that she gets in the curb but about 5 minutes into the ride, she had that lightbulb moment. I could literally see and feel it when she suddenly realized "Oh, that's what you've been showing me. Okay, I get it now." Now, she's riding almost like an old broke horse and needs very few direct rein reminders.
I swear, those are some of the most satisfying moments for a trainer.