Lift the right foot and rub with a foot scrub or any soap and scrub it with a pumice stone. Be sure to rub it well on the heel, on the outer edge of the foot and under the big toe. Scrub the nails well with a nail brush.
Cover the foot with modeling clay and let it dry while you repeat the same steps on the other foot. You can skip the clay if you lack the time or don’t have clay. By the time you’ve covered the second foot with a mask of modeling clay, the first one will have dried. Rub it vigorously until it starts to peel off. Then soak the foot in the water again and clean any clay left on the foot.