I learned of this drink from Sam Queen.  It is designed to feed the ATP cycle and so, to increase energy levels.

4-6 ounces organic, unfiltered apple juice (fresh juiced organic apples would be best)
2 tablespoons each fresh organic lemon and lime juice
Naturally carbonated water such as Perrier

Fill 8 ounce glass with apple, lemon, and lime juice and fill to top with carbonated water.