Answer:
You use me from your head to your toes. The more I work, the thinner I grow. What am I?
I start new then become old. Start clean but be one dirty. I usually start big then become little.
I am needed for most animals and hardcover books
I make you weak at the worst of all times. I keep you safe I keep you fine. I make your hands sweat and your heart grow cold. I visit the weak but seldom the bold.
I am easy to waste and unstoppable. What am I?
Some try to hide some try to cheat. But time will show we always will meet. Try as you might to guess my name. I promise you'll know when you I do claim.