Answer:
A mile from end to end, yet as close to as a friend. A precious commodity, freely given. Seen on the dead and on the living. Found on the rich, poor, short and tall, but shared among children most of all.
Vikings use this for warmth.
You seek it out, when your hunger is ripe. It sits on four legs, and smokes a pipe.
What has four legs during the day; and six or eight during the night?
Looks like water, but it's heat. Sits on sand, lays on concrete. A play on the eyes, but it's all lies.
I run through hills. I veer around mountains. I leap over rivers. And crawl through the forests. Step out your door to find me.