Lying 90/90 hip rotations

Start by lying down on the ground (supine), with your feet set wider then the hips, feet flat on the ground.
Rotate both knees to the left, by externally rotating the left leg and internally rotating the right leg.
The knee's should have a 90 degree angle.
Try and bring the right knee close to the ground behind the left knee, try and push it a closer towards the ground creating some tension along the right hamstring and glute.
Reset back to the neutral starting position and replicate to the opposite side.
To advanced the stretch and mobility you can stretch your arms out front, and then rotate them to the opposite side to the knees, creating more length throughout the spine.