I have a new mustang in training. He is really gentle and very smart. I am working with him slowly and I have also hired a trainer to assist me to the next level. I have noticed in my alone sessions of training he tends to fade about the 45-minute mark. He starts off willing and surprisingly is perfect, but as time goes on he disengages. It's like he doesn't want to play anymore. I see this as possible brain overload and usually let him go to be a horse. Bad? Good? In my observation, my trainer does not let him go and actually becomes more affirmative and a little aggressive which causes him to react negatively. Am I doing the right thing by letting him go at this time? This is the trainer's 3rd session and maybe her last. It starts off great but doesn't end well. Any advice is greatly appreciated.