Start standing with your feet together. Step your right foot forward into a front lunge. Make sure that both your front knee and back knee are at approximately 90-degree angles, and also make sure your front knee stays right over your ankle.
Push through the right foot back to standing. Then, staying tall, step the right foot behind you into a reverse lunge, again, bending both knees to about 90 degrees.
This counts as one rep. Perform these for one minute on each leg.