Hip Flexor Stretch.

Stand with your feet a few inches apart, then move one leg about 1 to 2 feet forward. Bend your knees, making sure your front knee is directly over the ankle, and your back heel is off the floor. Hold in your belly, and tuck your butt by tilting your pelvis. You should feel the stretch at the front of your hips. Hold for 15 to 60 seconds, then switch legs.