Cold and flu season - early prevention of a cold

Well, the cold and flu season is upon us and when I feel a cold coming on, this has helped me lots before:
Take some juice from half a lemon (press it out from a fresh lemon)
Put the juice and fruit in 300 ml of cold water
and mix in 1 teaspoon of honey

Drink this in the morning and evening. Make sure you do not use hot water, which would destroy the vitamin C in the lemon and the enzymes of the honey

I personally use organic honey as this one is not filtered, but any will do.