Before exercise, athletes should aim to be well-hydrated by drinking fluids throughout the day and consuming about 17-20 ounces of water 2-3 hours before exercise. During exercise, it is important to drink fluids regularly to replace sweat losses. The recommended range is around 7-10 ounces every 10-20 minutes, depending on individual sweat rates. After exercise, athletes should continue to hydrate by consuming fluids to replace any fluid losses. It is also recommended to include electrolytes in post-exercise hydration to help with rehydration and recovery.