Try dynamic stretching. There is a video at the followng link.
Swing one leg out to the side, then swing it back across your body in front of your other leg. Repeat 10 times on each side. Feel wobbly? Hold onto a steady object.
While standing tall, walk forward with an exaggerated backswing so that your heels come up to your glutes. When this is easy, try it while jogging. Do 10 reps on each side.
Get in a "pike" position (hips in the air). Put your right foot behind your left ankle. With your legs straight, press the heel of the left foot down. Release. Repeat 10 times on each side.
Lift your left leg up, bending the knee so it points out. Try to tap the inside of your left foot with your right hand without bending forward. Repeat 10 times on each side.
Keeping your back and knees straight, walk forward, lifting your legs straight out in front and flexing your toes. Advance this by adding a skipping motion. Do 10 reps on each side.
Step forward using a long stride, keeping the front knee over or just behind your toes. Lower your body by dropping your back knee toward the ground. Maintain an upright posture and keep your abdominal muscles tight.