Will this harm him mentally...plz read, only nice answers plz!!!?

that sounds good to me, but make sure you don't do it more than you have to. Maybe try mounting him in different places so he doesn't know what's coming. My horse has a similar problem and that helps. It might be a good idea to get someone to help you hold him. Also, don't take him to that spot you mount at only when you are going to ride. You can walk him over to the bucket with no tack just so he knows that the bucket does not always mean work. Good luck!