Remember you need Three (3)Things
The first 2 are Willpower & Wont power
Wont eat Junk food
Wont drink soda’s
and Wont eat Ice Cream
Will Exercise everyday
Will eat Healthy foods
Cycling, Swimming Tennis and Brisk Walking,
Skating is good too
Sound like hard work?
2 coin a phrase ‘just do it!’
The third thing you need is commonsense

Good Karma!
References :

"Most of the weight lost is water and not fat, and therefore not permanent. In addition, the recipe for the soup as often given has an extremely high sodium content, usually to make it palatable, and the diet provides practically zero protein for several days at a time. Many people report feeling weak and light-headed during the course of the diet."

Due to the lack of energy that the cabbage soup diet will give you, your energy stores in both muscles and liver will be greatly reduced, resulting in a lower body fluid content, which results in you feeling tired throughout the day.

Couldn’t you make the best of it and try to burn more calories than you are (healthily and sensibly) eating?
http://caloriecount.about.com/cc/calories-burned.php
http://www.prohealth.com/weightloss/tools/exercise/calculator1_2.cfm
If you use up 3,500 calories more than you eat, you will lose about 1 pound in weight
References :
http://health.howstuffworks.com/wellness/diet-fitness/weight-loss/cabbage-soup-diet2.htm