I am pretty weak in my core if I really want to be honest. I found out today I have not been using myself as I should. I am going to feel it for the next week. I was riding a near 18hh TB. He's pretty weak working to the right, and we worked so hard today, I think even he is going to be sore for the next couple days. But the canter I got out of him....
First time we cantered to the right, he bottomed out on me so hard I swear my ribs hit my hip. It felt like he was hopping along on his left two legs, that's how much he came off balance. It felt wrong, so I explained to my instructor and she said try this. I braced him hard with my right leg, I crossed my reins way over the left, and drove him with my left leg. He picked up such a collected, slow, smooth canter... I am overwhelmingly pleased with myself. We will both be sore for days but that canter was totally worth it. Just the way he sat back on his rear end, and drove from his rear end. I was so confused at first. I thought we should of been flying just from the power I was feeling, but it was so slow, so smooth.
I might be walking funny for the next few days, but there will be a silly grin on my face the whole time.
Think of it not as a failure but as a success in how not to do it.
Don't look in a horses mouth for a gift.