Interviewer: In the summer months you hear a lot about dehydration, and I've actually even heard that when you're thirsty it's too late. You're already dehydrated. So we're going to talk about that and other things about dehydration with Dr. Scott Youngquist. He's an emergency room physician at University of Utah Health Care. First of all, is there any truth to that, "When you're thirsty it's too late?" I'm already dehydrated?