Your hip flexors, which allow you to lift your knees and bend at the waist, are located on your upper thighs, just below your hipbones. To stretch your hip flexors:
Kneel on your right knee, cushioning your kneecap with a folded towel.
Place your left foot in front of you, bending your knee and placing your left hand on your left leg for stability.
Place your right hand on your right hip to avoid bending at the waist. Keep your back straight and abdominal muscles tight.
Lean forward, shifting more body weight onto your front leg. You'll feel a stretch in your right thigh.
Hold for about 30 seconds.
Switch legs and repeat.