Cardio isn't necessary to support the Iron Barre regimen. Cardio isn't really necessary for weight loss as caloric deficit and resistance training are key for actual weight loss. I encourage doing cardio for stress management, pursuing endurance training goals, or for cardiovascular benefits ( resistance training with little to no rest is a great way to achieve cardiovascular benefits). I HIGHLY recommend yoga, so that is wonderful you are including that in your training regimen. Resistance training or any type of exercise program should be balanced with yoga. If you enjoy the 20 minutes of steady state walking every day for achieving mental stress release or personal enjoyment, just stick with doing this. However, you will get more out of those 20 minutes if trying to lose weight by performing non-stop resistance training (or 30 seconds or less of rest between sets) to get cardiovascular benefits + improve lean muscle/metabolism.