One other idea (along with the stretches), ride without stirrups for short periods of time. Try it just at the walk, and imagine your entire body is a giant tree. Your trunk, head, and arms are the top of the tree while your hips, legs, and thighs, are the roots. Imagine your legs and feet are stretching deep into the ground, well below the horse. Keep your trunk as tall and upright as the tree and stretch your upper body up to the sky.
Focus on that feeling for a few minutes, then carry on with your riding. If you find yourself getting tense and your body is attempting to go fetal position on you, then come back to the walk and visual yourself as the tree for few minutes.
The more often you can ride correctly, then the more your body will start to do it through muscle memory. But you'll probably only be able to get the feel for a few minutes at a time to start with. Don't worry, it takes a while to recondition the body to a different feel and position. Just keep working on it. All of us (except maybe the super natural riders) have to work on it everyday, but it's worth it!
Posted via Mobile Device