1. Start by standing with good posture. Your feet should be hip to shoulder width apart, and your arms should be at your sides.
2. Take a big step forward, keeping upper body as straight as possible (see photo).
3. Lunge until your front thigh is parallel to the ground and your back knee is close to the floor.
4. Both knees should be bent at approximately 90 degrees. Make sure your front knee doesn't go past your toes.
5. Keep your eyes looking straight ahead, and don't look down.
6. Return back to the standing position, alternate legs and repeat. Do 3 sets of 10-12 reps on each side.
7. As the exercise becomes easier, feel free to make it more challenging by adding light dumbbells.
Also see: Strengthening Workouts for Runners