Hi sweetie :)
I can guarantee you that you are not alone with this dillema. Even I can be handsy and I have to force, force, force myself to soften up and let go. There are THOUSANDS of riders out there who have the same exact problem.
The issue is, is that this is what we are all permitted to do when we ride in lessons, or are never shown otherwise. Most horses put up with it or don't know any better just like their riders.
So let me stand up and applaud you for realizing your issue, and wanting to fix it - not only for you, for you to become a better equestrian, but for your horse. To make you that much better, to make your horse that much better.
Lets start by looking at the Spanish Riding School in Vienna. The riders, as I've said before in other threads, start out at that phenominal school on a lunge line for a whole year. Not just a lunge line, but without reins.
Why? So that these riders can learn the classical way of riding - seat first. If you watch their video's on youtube or if you ever have the honor of seeing them in person, you'll see how well educated their seats are. They are taught from day 1, proper balance, educated seats, legs and how to use them first and foremost. Hands aren't even in the picture for a whole year.
So, lets come back to the majority of riders in North America. We have coaches who don't spend this time with their students. Lets admit it, majority of us are plopped on a horse and taught how to walk, trot, canter, halt before we even know what a seat is.
I blame the coaches, absolutely 100% - the reason why we have so many uneducated riders out there, including myself. I am 33, and I am learning things that I should of learnt 15 years ago.
Back to the point, how do we learn to ride without our hands? Re-education.
Lets first ask why we use our hands so much? Not only due to our Coaches not teaching us properly *either they don't have the time, or they don't know themselves* We must learn to re-balance ourselves.
Our seats first and foremost. I was shown to ride SEAT into LEGS into HANDS to SOFTEN.
Ok, so it is one thing to just read that on a computer screen, but another to learn how to do it, and learn how to do it correctly. I highly recommend you find a coach who can show you this in person. Someone who can help you in person. Show you how to use your seat first, put you on a lunge line with no reins and aid you step by step to help you.
I was able to learn at clinics. I would never of obtained this information if I didn't have someone show me in person.
I remember David O'Connor showing those who signed up for his Clinic how to use seats first and hands last. He got onto a clinitians horse and held the reins at the buckle.
He was able to use only his seat to bring the strange horse from the canter, to the trot. From the trot to the walk, from the walk to the halt - all just by knowing how to slow his seat down.
It was amazing.
I am riding under a Dressage Coach now. She not only boards at the barn I am at, but she compete's 3rd level and wholeheartedly believes in Seat into Legs into Hands to Soften.
She is showing me how to soften my hands and my elbows and my shoulders. I am amazingly surprised at how Nelson is reaching for the bit, and rounding and working from the back end.
The moment I tense up my shoulders, my elbows, wrists and fingers - he braces against me.
I have been shown how to ride with just my thumbs and index fingers. I am absolutely thrilled with the results I get from Nelson. It is amazing.
I use my seat and my legs to get the forward, fluid momentum that I want from Nelson. With soft hands. I am not collecting Nelson, I don't have a short reins nor do I have long reins, but just inbetween, with soft arms/hands, while still yet feeling contact with his mouth. I use my thumbs and index fingers only and allow Nelson to open up front.
The moment I feel him shorten up and drop his back and tense up - I open my arms. Meaning, I take my elbows off my sides, and open my elbow angle - allowing him to stretch out and soften up again.
All the while, using my seat and my legs to keep the rhythm desired.
Anyways, the point is - so many riders use their hands first to get the desired effect they want, when instead they should be resorting to their seats and their legs.
How many turn with their inside rein? How many ask for halt with their hands. The list goes on and on and on and on. So many of us.
Anyways, I can go on and on and on - as everyone on here already knows. lol.
My answer, is find someone who can put you on the lunge line, with no reins. You'd be amazed at how that helps. I do it, so can you. Learn to ride with your seat first, figure it out. Figure out how to use it to engage. Use it to slow your horse down. Learn to turn with your seat bones and legs. Etc, etc, etc
Start with that.