• Place the right knee on the ground roughly in line with your left shoulder
• The right foot should be just in front of the left knee
• Press your hips towards the ground so that your bodyweight is on your right leg.
• As you move down the right knee comes closer to the left shoulder.
• You should feel a gentle pull deep in the right hip / buttocks.

For further information about overuse injury of the piriformis muscle read, the piriformis syndrome article.