Two workouts can last the same amount of time and leave you needing very different amounts of fluid. A calm gym session in air conditioning is not the same as running outside in humid heat. Your plan should fit the workout, not a universal bottle count.
This guide walks through what to do before, during and after exercise, how to judge when electrolytes may help, and how to estimate sweat loss if you train for long periods. It also explains why drinking too much can be dangerous.
