Answer:
My life can be measured in hours. I serve by being devoured. Thin, I am quick. Fat, I am slow. Wind is my foe.
What gets beaten, and whipped, but never cries?
Sometimes I am loud. And viewed with distaste. Poke out my 'eye', then I'm on the front of your face.
It is by nature, soft as silk; A puffy cloud, white as milk; Snow tops this tropical crop; The dirtiest part of a mop
I dig out tiny caves and store gold and silver in them. I also build bridges of silver and make crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs my help. Yet many people are afraid to let me help them.
People take me on walks and I run and have fun. What am I?