He has the most AMAZING techniques. They are so incredible. Good luck!

Ground work, ground work and more ground work. Go back to the very basics that she probably never had, even at 19. She is probably just reacting with fear and a lack of confidence. It will take patience and time. I would not lunge her. I would teach her to go away from me and return, move left, right, forward and backward. Teach her to respect your space. Introduce lots of lateral flexion and teach her head down which is very calming as it shows tremendous trust from her. Help her to relax. Control her mind and you can control her feet. When you accomplish this on the ground, it translates pretty easily to under saddle. good luck

I had an ex-race horse for a long time ^-^
He to was also high strung and I would do a couple of things to make him less so
Lunging your horse before your ride them and even just to get them out of their stall is a good way of relieving some tension and energy, this also helps let your horse start to calm it’s self and get used to it’s surroundings.
Another thing is to try riding western and working on basic training, such as bending around your leg, getting on and off the horse with out your horse moving, and tie your horse up and letting them stand around for a little while.
Riding on trails in another thing I find helps. You should do this after you’ve worked your horse, maybe ride around the yard or neighborhood if you can. This lets your horse start to get used to things and causes less things to spook or excite her.
Try to let her do calm things. Just like with people when you want them to calm down and make them more mellow you make them take a deep breath and slow down what they are doing.
I hope this helps ;D