Okay, call me stupid if you'd like.
While I realize it's important to drink water--and I always drink at least 64 ounces of water before I teach a class or take a class--it never occurred to me that aside from sweat, there are other ways to lose water from the body. Yes, I know it's ridiculous and as an educated adult I should know better.
This came about (ironically) in a CONVERSATION with my supervisor at work. We were discussing healthy habits to have, and she mentioned drinking water as critical because we lose so much water just by talking. It never even occurred to me that when we talk we do expel water from our mouth. I mean sure, every so often we laugh so hard or speak and "spit" a little by accident, but I never thought that with each word I expressed, water was also being lost in the process. Go figure.
We also obviously lose water when we go to the bathroom and quick research also tells me that we also do lose water through respiration. So even when we're sleeping and breathing, we're losing water (I must breathe a lot at night, ha ha, since I get so thirsty sometimes).
So then, friends, how do you know you need MORE water? If you haveLittle or no urine, or urine that is darker than usual; dry mouth; sleepiness or fatigue; extreme thirst; headache; confusion; feeling dizzy or lightheaded; or have no tears when crying. Of course, by the time you experience these symptoms, you're already dehydrated so take a proactive stance and hydrate regularly :)