Summarize:

The measurements don't have to be exact. If you are using fresh lime juice, you will need about half a lime. If the drink is too sweet for you, you can add a little bit more lime juice. If the drink is not sweet enough, you can add more sugar. You can also use sugar packets. Each sugar packet contains about 1 teaspoon of sugar. Some people find that this is a good remedy for hangovers.
Fill a glass with 8 to 10 ounces (236.59 to295.74 milliliters) of cold water. Add ½ teaspoon of lime juice to the water. Add 2 teaspoons of sugar to the water. Stir the water and enjoy it.