Aggressive... striking... rearing.. the challenges here go way beyond rearing. This filly needs a whole lot of basic ground/longe training before you ride her. Fillies, by the way tend to be about a year behind the boys, so a filly that's coming up on 3 is really about 2-2 1/2 physically, mentally and emotionally! She needs to be mentally engaged and she needs to move forward and she needs to keep all 4 feet on the ground. I have an exercise that I use with horses like her- it is so simple, you won't believe that it can work well, but others have called it "Leslie's magic barrel pattern" because it works wonders. Here's how it goes: Set up 4 barrels about 20 feet apart, making a square. Lead her in a cloverleaf pattern around the 4 barrels in the same direction until she settles into the pattern. Then direct her through the pattern, you are on one side (inside) of the barrel- direct her all the way around each barrel ( 1 1/4 turn each time around) asking her to look at the barrel by tipping her nose towards it and then lead her (you are on the inside of the square) to the next barrel. Do this pattern in the same direction over and over again. She will focus on the pattern, focus on the barrels, focus on you... and she will be engaged and will button down. From here, you ask her to walk circles around all 4 barrels, expanding the work area, but staying near the barrels. You will return to the pattern often to focus her mind, keep her feet settled. You will do both sides, and you will add this to your teaching sessions for as long as it takes for her to mentally and physically settle down. I have used this on very aggressive horses- works wonders. I've used this with super-flighty, can't keep 4 feet on the ground horses... works wonders. I've used it with very sensitive, distracted babies... works wonders. If you need more info, want me to send an illustration of the pattern- contact me privately and I'll send it to you.