Don’t confuse this advice with a wild card to drink a couple of glasses of water a day. “If you’re thirsty before a workout, drink 16 oz. of water right before you start; may be add some electrolytes,” Williams says. They are helpful in preventing dehydration. “But don’t drink a lot at once because it will make you feel really full, not allowing you an effective workout.” In addition to having to go to the restroom all the time, your kidneys will suffer. They can process about a liter an hour. Making them do more than that can lead to hyponatremia. This is when the level of sodium in the blood is too low.