In a kneeling position thighs and body perpendicular to the ground, the knees and lower legs approximately two fists apart.
Pressing the knees into the floor, strongly rooting from the navel lift away from the lower back, slightly tucking the tailbone, feel the expansion of the chest upwards as high as it can go before you lean back, grasping the heels and pressing the heart center up towards the sky. Before you go back, arch the chest as much as you can, pull your chin in to connect your neck to the upper spine. Allow the head to go back as far as it can without disconnecting it from your arch or compressing the neck.
Back bends are supposed to feel great, the spine is being elongated, the front of the hips opening and the lower back protected by a strong root lock/ navel drawing towards the spine. Breathe.
Let the head fall back, as far as the heart center/ chest allow. Press the hips forward keeping the head above the feet.