A dry mouth doesn’t automatically mean danger. But thirst is your body’s way of reminding you to reach for your water bottle when you’re on your way to becoming dehydrated, so don’t ignore the obvious. According to the Institute of Medicine, men should take in approximately three liters (about 13 cups) of liquid a day—but that’s just a baseline. If you’re exercising in hot and humid weather, you’ll need to fill up on more fluid. Sick of plain ol’ H20? Keep in mind that water-dense fruits and vegetables, like celery, cucumbers, and melon, also help with hydration.