Of all the reasons H2O (preferably filtered) is oh-so-good for you, the work it does for your guts is one of the best. For starters, it helps lubricate everything, so food can slide through more easily. Plus, it helps quell hunger and fights bad breath.

Your mechanism for detecting thirst weakens with age, which makes it that much more important to remind yourself to drink regularly throughout the day -- before your body even tells you it's time.

You've probably heard that you should drink eight 8-ounce glasses every day, but there’s no magic to this number. And the right amount varies according to your activity level and size; just drink enough water so that your urine is clear.