Seated Twist

Sit on the floor with both legs extended in front of you, then bend one knee and cross that foot over to the outside of your opposite thigh. Plant that foot, sit tall, and rotate your torso toward the bent knee, using your opposite elbow against the outside of it for a little extra leverage. Keep your sit bones grounded and your spine long rather than collapsing forward as you twist; the rotation should come from your ribs and lower back, not from folding your shoulders around. You'll feel this through your lower back and the outside of your hip on the bent-leg side. Come back through center before setting up the other way.