I am 13 and I have knock knees, but the shape of my legs changes regularly. Can you tell me some exercises I can do?

Start by correcting imbalances in your feet by strengthening and stretching your muscles and ligaments and increasing your overall awareness of your feet and toes. Walking barefoot, rolling a tennis ball under the arches of your feet, rocking back and forth onto your toes and heels, and massaging your feet can help you over time to enhance the functionality of your feet, which is the foundation for proper alignment of your ankles, knees, hips and spine. Secondly, to address your knock knees, you should be strengthening your abductor muscles to balance strong adductors, which contribute to the condition. Some of the exercises include side-lying or standing side leg raises, one leg side bridges, and prone straddle holds. Look into structural alignment or yoga therapy for a specific set of exercises. Do those consistently, and your knock knees will improve over time.