Start with the walk. Ride figure eight with circles of uneven size. One is small 8-10 m and another is bigger 15-20 m. Ride small one as a regular circle. Ride bigger one in counter shoulder-in. You do not need to ride the whole circle in counter shoulder-in, only part of it. Ride one direction until it feels good and your horse feels supple and balanced. Change directions. Again, ride until you feel him supple that he changes direction without any disturbance in his rhythm. You change the bend in this exercise during the whole figure eight. Next try to do renvers instead of counter shoulder-in. Do not aim for a lot of bend, renvers on the circle is hard for a horse. When coming to a big circle for the renvers you already have the bend. You can keep it and develop renvers. Next, try it in trot. You can make circles bigger for the trot and ask for less bend in counter shoulder-in and renvers. You can even try this exercise in the canter, it is really good for straightness and flying changes. Ask for even less bend in the canter. Be flexible and playful, aim for responsiveness not for amount of time in counter-bend. Request a good bend and engagement on the small circle. Do not work on this exercise for a long time. Give your horse a lot of brakes. If things are not really working in the walk, do not skip it to go to a trot, it will not work in the trot neither. Spread this work over several rides until you start to feel that things are coming together.