I'm not sure what this means. Does it mean a ride that changed the course of your life? I suppose the Confidence Shattering Fall would fall into that category. My life was definitely not the same after that.
Horses did well for the vet. Royal had to get 4x the normal amount of sedation for his power float. And he still wasn't fully out, from the way he noticed every single time someone talked or a horse moved. Figures. That's why it can be so hard to get him to pay attention: he just always has to know what's going on.