A subtle coordination of the head and spine to support the bending of the leg–it just may put a spring in your step in the middle of winter (for those of us in the Northern hemisphere, that is!).
You may want to have a few flat, firm cushions or flat, folded towels for under your head as you lie on the side. Depending on the organization of your spine, shoulders, and neck, you may be able to do it without. If your neck is strained, that’s an extra barrier to feeling the dynamic connection with your pelvis and legs.