Drink lots of fluids. Colds and flu can wreck havoc on your body, often depriving it of much needed fluids. Replenish these by drinking plenty of water or energy drinks when you’re ill. A rule of thumb is to drink half your body weight in ounces at a minimum. Always strive to get half of the water in by noon. Keeping up a healthy water intake will reduce the number of illnesses you get.