Peel and finely chop the ginger and put it in a saucepan with the sugar and 2 mugs of water. Bring to the boil and reduce the heat. Simmer it for 8-10 minutes. Turn off the heat and add the juice from the lemon and serve. Lemon oil is also good for colds and flu and other people (my mate Big Alex, for example) recommend slicing the lemon and adding it as the water is boiling. I don't recommend this unless you get to pick the lemons from the trees yourself as most commercially available lemons have been treated with wax containing various poisons. I got a chance to pick lemons in Spain in an old abandoned and overgrown orchard. The skin of those lemons were very different from what I was used to. They were not shiny and smooth like the shop lemons and they released their smell with the gentlest touch. I have seen unwaxed lemons for sale but not often and for a high price.