Half pigeon is a favourite of many people, but not appropriate for everyone.
It is great for opening and releasing through the outer hip and glute (on the bent leg), and can also provide lengthening through the front hip and thigh on the straight leg.
However, if this pose causes any pain in the bent knee, an alternative pose should be chosen (see below).
From Down Dog, raise the right leg and then sweep the leg forward, bringing the knee directly behind the right wrist and the foot over towards the left side of the mat. Keep the hips square to the front and level with one another. If the right hip is raised, place a block or blanket underneath for support.
Position the shin at an angle appropriate for your knee. For most people, this will be about 45 degrees. Keep the foot flexed to protect the knee, especially if the shin is closer to parallel to the front of your mat. If your shin is at more of a diagonal angle with the foot close to the groin, the foot can be more pointed. Experiment until it feels right.
The left leg slides back as far as possible, pointing directly behind your left hip. Toes should be untucked, the top of the foot on the mat.
Once the legs are set up, lift your torso, engage the belly and lengthen through the front body, then walk the hands in front of you until your torso has folded forward. You could rest on your elbows or lower further and rest your forehead on your forearms or the mat.
To make this pose active, press the top of the foot into the mat, engaging through the thigh and slightly raising the knee off the floor. Reach the hands in front of you and come onto the finger tips, raising the elbows off the floor and drawing the armpits down towards the hip.
Alternatively, a yin approach is to soften everything as much as possible. More props could be used, such as a bolster under the hips or under the forearms to support the upper body. (This pose is called Sleeping Swan in a yin practice, and would be held for 3-5 minutes on each side).
Hip openers can bring up emotions, so don’t be surprised if this happens in Half Pigeon. Try to focus your awareness on your breath, taking long low breaths in and out of the nose.
If this pose is inappropriate for your hips or knees, doing it on your back allows you to control the depth for the hips and the flexion for the knee. Cross the right ankle over the left knee and draw the knees towards the chest by wrapping the hands around the left thigh or shin. Keep the shoulders and head on the floor and use a strap if you cannot reach your hands around your left leg.