Maybe he wasn't 100% quiet haha but he was/is 24 and takes care of his rider. HE JUST DOESN'T LIKE BEING ALONE.
This is a horse,
any horse, in a nutshell. They are herd animals, so a lot of what they do is the result of a "herd mentality." One of my pet sayings is, "when one horsey runs, all horsies must run." They may not know
why the other horse is running, but if it's because of something dangerous, staying behind means "dangerous" happens to them - so they run, too, just in case. Besides that, running is fun. That's not being bad, or a lack of training, or anything else, it's just a horse being a horse. Most of the time, if you watch a group of horsemen and one or more leave the group (especially at speed), you'll see at least some of the remaining horses toss their heads or dance around a bit as they instinctively react to being left behind. A good rider learns to think like a horse; to look at a situation as the horse would, and anticipate the horse's response. So, though the instinct is to move, the rider says, "no," so the well-trained horse does as he's told - pretty much, anyway.
If you have anxiety issues, dealing with horses can make you better or worse; your choice. Because as you said, the horse feeds off of your energy, so if you are nervous, the horse gets nervous, and it can become a vicious cycle. Or, you can choose to short-circuit that system by refusing to get in it in the first place. You train yourself to see what the horse sees, and anticipate and deal with the difficulty before it happens. For example, I know that Syd has a problem with things that flap around (think flag). So if I see something ahead of us that is moving in the breeze, I can expect that Syd might spook when we get near it. If I watch her closely, she will tell me about her rising nervousness - ears working back and forth, head raised; maybe even moving sideways a little - and I can gently but firmly encourage her to move forward past it. If she
does spook, I am ready for it, because I knew about the spooky object, and can bring her back under control quickly because I am not taken by surprise. My attitude in such a situation is, "when you are done being silly, we'll get on with this." If she
doesn't spook, I praise her, because she paid more attention to me than to her fear. They say that there is no free time with horses; any time you are with them, they are learning something. In the situation I described, Syd is learning that she can trust me to do the thinking, that I won't get her into trouble, and I learn that Syd is learning to listen and not just react.