You use me from your head to toe. The more I work, the thinner I grow. What am I?

Why this works

This riddle cleverly plays on the dual meanings of "use" and "work." A bar of soap is utilized all over the body, from head to toe, during washing. As you use soap, it lathers and cleans but gradually diminishes in size, hence "the more I work, the thinner I grow." The riddle invites you to think about an everyday object that transforms as it fulfills its purpose, making the answer both logical and relatable!