Sometimes, I question which direction i should approach certain issues, such as hydration.   

Doctor perspective: We should all be drinking at least 1/3 of our body weight in fluid oz of water per day + 8 oz for each vice.  For some of smoking patients, that last part is overwhelming, but it is crucial.  A vice can be one cigarette or one cup of coffee or one alcoholic drink.  So, if you are a pack a day smoker and you weight 150#, you should be drinking at least 210 oz of water a day!  This alone might be a good way to help cut down on the number of cigarettes you smoke.  You should also drink 8oz of water for each 20-30 minutes of exercise.  So, the 8 8 oz glasses theory is not really meant for a one size fits all because it is possible to overhydrate (although very uncommon).   

Athlete perspective: As a runner, I know the importance of staying hydrated before and during workouts.  I would look at the sports drinks on the market and my doctor side would shine through.  How could something with tons of sugar, food dies, wheat or similar be any good at rehydrating a person?  In my search I found Nuun, a Seattle based company and my new favorite drink post runs.  It does not contain any of the above mentioned ingredients and it does what it should do; helps to rehydrate or stay hydrated.  

Multiple Sclerosis patient perspective:  Due to the first two thought processes, this one is more difficult.  I know what I should do; but I also know what my body will allow me to do!  Although I do not have any bladder issues with my MS, for some reason, when I start to run, my bladder feels irritated.  I could stop every minute if I let myself, but it would not help the situation.  Due to this, I do not drink during any of my workouts or races.  I know, this is not optimal, but it works for me. I make sure I drink plenty of fluids the day before a big race and drink a ton once I cross the finish line.  I think drinking something like Nuun helps to keep me hydrated during the runs.   

Take home point - Water is a necessity for everyone!  However you stay hydrated - drink your water.  And, if you are someone who likes electrolyte type drinks, make sure to read the labels and know what you are drinking.   

Note:  I am not affiliated with Nuun just happen to love the product.