Think about this: Gravity pulls everything down, but somehow blood moves from the tips of your toes back up to your heart.
Every second of every day, your body works against gravity. You can jump, hop, and stand up from a chair. All of these things require upward motion, against the pull of gravity. But in some ways, your body does not work against gravity. Over time, its pull takes a toll and causes changes you might not even notice from one day to the next.
