How much water should I drink?
There is no universal glass-count that works for every body, climate, diet, and training load. Start with thirst, urine color, energy, and performance. If you are rarely thirsty, urine is pale yellow, training feels normal, and you are not getting frequent headaches, dizziness, or cramps, your hydration is probably close enough.
Needs rise with sweat, heat, elevation, high-fiber diets, higher protein intake, salty meals, alcohol, illness, and longer training sessions. They can also fall when food intake includes more soups, fruit, vegetables, yogurt, and other water-rich foods.
For sweaty workouts, weigh yourself before and after training occasionally. If you finish much lighter, most of that short-term drop is water loss. You do not need to replace every ounce immediately, but large repeated drops suggest you should drink more before, during, or after similar sessions. If sweat losses are high, especially in heat or long endurance work, sodium and other electrolytes may matter as much as water.
Do not force extreme water intake. Overdoing water without enough electrolytes, especially during long endurance events, can be dangerous. The target is adequate hydration, not maximal water consumption.
Most people should focus on the major signals: Drink with meals, drink around training, respond to thirst, and adjust when your urine, energy, digestion, headaches, cramping, or performance suggest the current pattern is not working.