Kneel down on one knee.
Ensure your rear knee is directly under your hip and your front knee is in line with your front heel.
Now tuck your bottom under, opening out through the front of the hip you are kneeling on.
To increase the stretch, gently lean to the opposite side and place the arm of the same side you are stretching up above your head and stretch towards the ceiling.
Maintain the position for as long as prescribed.