I have one of these. I got him as a 5yo, he came off the track at the end of his 4yo year, spent a month with a rehab/adoption program, and was adopted. While at the program, he was ridden, jumped in the ring, XC schooled by young teenagers. He was handled on the ground by kids. He was quiet, easy, and perfect.
He was returned to the program six months later very underweight and frantic in every way. A bird could sneeze two miles away, and he would hyper focus on it and be anxious. Never spooky, but very high tension and worry about everything. His issues ended up being a mix of physical and emotional/mental. I don’t know 100% what happened to him in that six month window with his previous owner, but it was not good. He was returned because he was “too nervous to show.”
His teeth were atrocious and he had severe bruising all through his mouth from his molars. He also needed several chiropractic adjustments to get all of his parts working together. Before I had that done, he could only go one direction semi-controlled. The other direction was out of the question.
His emotional state was also really challenging. Even on the ground, he was well behaved and very well mannered, but he functioned at a baseline of anxiety/stress that was high and impacted every part of his life. I spent a LOT, and I mean a LOT of time with him. As in 2-3 hours every single day.
I do a lot of ground work naturally as part of our daily routine, like I do not go out of my way to do a “groundwork session”, it just becomes part of what we do each day. Move out of my space, or stay with me, back up, focus, let me move your shoulders, etc. Getting his focus on me and his confidence and comfort with me was key. They have to seek you out as a calm place that they can look to and not mentally escalate because once their brain hits that anxious threshold, it’s very hard to bring them back down, and they don’t learn/retain well when they’re that “up.”
I have to be very kind and relaxed but also confident and clear/decisive with him. A lot of it comes from your natural demeanor and presence around them, and the relationship you build with them. With riding, I had to learn to be a much softer and balanced rider. I was not when I bought him but learned out of necessity. I still spend every single day with him, several hours, because that is our routine and what we both like.
He’s quiet and easy most of the time now, and when he isn’t it’s due to a physical issue (he has quite a few.) He becomes tense/anxious/unfocused due to pain (which is fair.) He is kind, he is sweet, he is honest, and he wants to please. He has never been a scary horse, in the eight years of owning him there is not one instance where I’ve been afraid of him. That said, in the wrong hands he would probably become deadly because someone would either walk on eggshells around him OR really bully/man handle him.
Warwick Schiller has a great YT channel for this kind of thing, 10/10 recommend checking him out. He has groundwork and riding videos for all types. Putting in the time to build the relationship and trust with them will improve every aspect of you and your horse, on the ground and riding.
One tip that really helps is not being robotic or “follow ABC steps to get XYZ result.” Going by feel and by listening to your horse’s responses/answers and working from those vs “but the steps say…!” will help a lot. Horses have a lot to tell us, we just have to listen
Very long story short, it can be done and can be very rewarding, but it’s hard. Just plain hard, sometimes seems impossible, but it’s not. My horse is now 12, and we’ve evented, show jumped, done dressage, hack out regularly, ride bareback (he was good, but those withers YIKES.) “Too nervous to show” my rump roast Chin up, it will get better! This happens to a lot more people/horses than folks think. What you see online is a “best of” and not reality.