Horse rears on the lunge line?

Well, my mom's arab had the same habit for a while. Now I am not the type to hit horses, but in this case your need to protect yourself at the same time you are trying to help her through this. I dont know if you usually carry a long lunging whip with you but try bringing one the next time. First ask her to walk (dont use the whip) if she does, good. if she bolts, let her run until she comes back down to a walk because there is no point in fighting with her to slow down, because she wont. If she slows down to a walk w/o rearing, good but if not: as soon as she rears point your hand (with the lunge line in it) in the direction she is supose to be going and quickly walk or even run torwards her and snap the whip next to her (try to think of the whip and pushing her away with it) I know this all sounds dangerous and scary but she has you convinced that she is bigger and in control. She will not like this so be prepared but after she tests you a couple time and you show her that you have the power to be bigger (with the whip) and have more power than her, she is likely to just do what you say and give up the habit. Hope this helps