Head to Knee (Single-Leg Forward Fold)

This common runners stretch really hits the hamstrings and glutes, and helps prevent lower-back pain.

Sit with both legs extended in front of you. Bend the right knee placing the sole of your right foot against your left inner thigh.
Fold over your left leg. Rest your hands on the floor on either side of your leg or on your shin, or wrap your hands around your left foot.
Breathe deeply, performing this stretch for three to four minutes on each side.