Question: This mare is very good with any thing asked of her until you tack her up an get on then she's in a fast running walk non stop. This has been on a lounge line with a rider on her.  With out a rider she's doing great.  As for control, there is none, she  has a very hard mouth an bits make no difference. She goes fast with no control diving in at the person holding the lounge line {with a rider}  after the rider is off she's very calm again. Almost like a race horse coming out of the starting gate.  I have no clue what to do about this.

If she's good on the ground and with lunging, etc., go back to the beginning training(whenever there's a major problem, there's usually a "hole" in the basics, so "review," find the hole, correct). Review commands, including verbal, on the lunge line....especially to WALK, and stay calm. Reward for staying calm and relaxed. Work on maintaining complete control on the ground, thru all exercises. Take a few days or so without the saddle, then continue with the saddle,maybe even a bridle(but hook lunge to halter under, can eliminate reins) but on one getting on her. Reward for a good session. I suspect that at some point, she was asked for too much too soon, and has been overwhelmed; work has not been a pleasant experience, she wants to leave the scene!

After a week or so, depending on how she's doing (using the time to develop TRUST, as well as control-do NOT rush to next step), during which also, perhaps before and after each session - spend time grooming, relaxing in a set of SAFE crossties. ALso get her used to having 2 people around, and working around her. Do this after, with the saddle still on, too.  When you feel its "time"(based on her relaxation and calm responsiveness), hook the reins back on, but leave in crossties. Practice mounting....for which she should stand quietly....and just sitting calmly on her, stroking and talking softly to her. Do this for about-at least - a week, so she learns not to anticipate having to take off. Its best, once she's doing this well, when back in the roundpen, to have the second person lead her from her head, on a shank to the halter, the rider with the reins, in actual command. Start by repeating what you did in the crossties....just mounting, standing quietly, dismounting....you may want to just to this for a day or two, or more...til she calms. Then, just ask for a walk.....avoid lunging, she may relate this with moving out fast, as that is what most people do with the lungeline, without a rider, and she may be queing to move out from the groundhandler, instead of the rider. For your own (or whoever rider is) safety, have the groundperson lead at the head, which they relate more to walking calmly. Just work on walking calmly and halting; reversing, walking calmly. Do this for a week or two, gradually "weaning" to more length on the lead, the groundsperson dropping back some behind the head, then eventually no lead with groundperson walking next to...then weaning the
groundsperson back away from the horse.....just concentrating on walking calmly and control. Make sure to use a rider that has enough confidence to give her the RELEASE on the reins enough, as a reward for when she does right. 

Its rather human nature for an inexperienced person, when a horse prefers going fast, to stay too much in a horse's mouth, maybe even squeeze with the legs (a signal to go fast!), when that's exactly what the horse wants to escape- the steady pain of it...and a horse's main means of escape is to run, or otherwise go fast! SO make sure whoever is getting on, can get their bodylanguage calm and relaxed as well, and give the release at the appropriate times, when needing to stop - use the three-strike method....ask very gently
first, then a bit harder, third time more seriously....given the choice, horses will quickly
learn to respond to the gentlest cue..... 

This is a matter of retraining the horse(but also, for humans to find the error in training, and also find and correct any errors of their own), and its best to start right from the very beginning....no horse is too old to re-learn....it just takes a bit longer, but only at first, than starting with a "clean slate"....you must "erase" old bad memories first. Just have patience, take your time, and eventually you will be highly rewarded.....we already know she gaits
well! But if you dont have control at the walk (the easiest place for us to gain it), you will have a harder time at anything else.

Stella