I have a 5 yar old mare that I've been jumping. She loves it , but she gets a little too excited. If we go over a 2 12 inch "jumps" in a row at a trot, she jumps them and then tries to buck/ run off. I tried walking the fist one then trotting the second, and that works, but then I try trotting both and then she runs/ a little buck thing after ward. I pull her head up and slow her down, but it keeps happening. Any suggestions / exercises I can try?