Ive never went on a juice cleanse, but I did find drinking vegetables intersting since I don't usually eat them. Fat, sick and nearly dieing had a great recipe you might want to try
6 kale "leaves"
4 cellery stalks
thumb of fresh ginger
half a lemon
a cucumber
4 apples
first time I drank it I was expecting something nasty, but it actually tastes pretty awesome.