Watch the above video and/or follow these instructions:
Start sitting down with your feet hip-width apart.
Do this exercise one foot at a time.
Pull your big toe out and way from your other toes as far as you can and anchor it to the floor by pressing down hard. Try to make it as straight as you can.
Keep pressing down hard with your big toe knuckle and you will really feel this working under the arch of your foot.
Now release the toe, lift it up and then repeat this exercise again two more times then do the other foot.
This exercise helps to reduce the valgus position, reducing joint inflammation and strengthening the muscles under the arch of the foot.