Answer:
Feed me and I live. Give me water and I die. What am I?
Ten men's strength, ten men's length. Ten men can't break me, yet a young boy walks off with me. What am I?
I run up and down the stairs without moving
I can run but not walk. Wherever I go thought follows close behind.
I move without wings, between silken strings. I leave as you find my substance behind. What am I?
No matter how little or how much you use me, you change me every month.