Drink your 8, 8-oz glasses of water a day, or equivalent! Your serum Sodium levels (related to the water you drink) should be less than 142 mEq/L.
"Adults who stay well-hydrated appear to be healthier, develop fewer chronic conditions, such as heart and lung disease, and live longer than those who may not get sufficient fluids, according to a National Institutes of Health study published in eBioMedicine."