We have already discussed that you should be drinking 1/2 your weight in ounces of water each day. Current recommendations also suggest that you should add 5 ounces of water for every 15 minutes of exercise. Given that we should be logging at least 30-60 minutes of exercise each day that is another 10-20 ounces we should be consuming.
The key is to make sure you are hydrated enough to keep your organs functioning through your workout. You also want to replace the fluids lost through sweating. Adding some unrefined sea salt to your water is a great way to add back some minerals and electrolytes to your water.
In exercise, as well as in daily use, it is a good idea to get used to drinking water at room temperature. Water that is too cold or too hot will cause damage to the mucosal lining of the stomach in susceptible individuals.
So when you are packing your gym bag make sure you are planning for enough water!