Ockham’s Thrist Posted byGarrick van Buren July 30, 2012 Should people who exercise seek to proactively replace fluids lost, or can they rely on thirst to guide them during and after physical activity? And when they rehydrate, do they need all the salts, sugars, and other ingredients dumped into sports drinks, or is water fine? The correct answers are: best to rely on thirst, and water is fine.