Answer:
Santa shakes his belly like a bowl full of me
After you go through a fall, I will take over. All life will stall, or at least grow slower. What am I?
By myself, I'm practically nothing. Worthless as a leader, but when I follow a group, their strength increases tenfold. What am I?
I jump when I walk and sit when I stand.
With a halo of water and a tongue of wood; stone as skin long I stood.
I run through hills. I veer around mountains. I leap over rivers. And crawl through the forests. Step out your door to find me.