The Master Cleanse is a strict daily routine consisting of:
(1) begin each morning with a salt water flush
(2) throughout the day drink 6~12 cups of master cleanse lemonade mixture
(3) each night, end the day with a nightly herbal tea (a herbal laxative tea / peppermint tea / camomile tea)
The fast usually lasts 10 days, but some choose longer periods of time.
The theory is that during the fast, the calories and nutrients in your regular diet are replaced by those from the lemonade, which must be taken 6+ times a day.
As many glasses of lemonade as desired may be taken beyond the minimum required. Water can also be taken as desired.
For the best results I should follow the daily regimen strictly for a minimum of 10 days. This does seem very daunting a goal for most people, however by day 3 or 4 you should start to find it much easier and be able to visualize yourself making it to day 10 without much hardship.