Set up: Kneeling with one foot out in front, aiming for 90 degrees at the knee joint of both the font and back leg.
Maintaining neutral spine, slowly and gently lean forward until you feel a stretch through the hip flexor muscles at the front of your hip, you should feel this on the side which has the foot behind your body. To increase the stretch, squeeze the glutes and tuck the tailbone under (posterior tilt of the pelvis) as you lean forward. Hold for 20-30 seconds before changing sides.