According to the book, you should do a minimum of 10 days. I'm not a good adviser except to say that I've been where you are and attempted the fast only to eat on day 2 because I was so miserable. I will tell you, I would give ANYTHING to go back and just stick it out because it WILL pass! (Yes, I'm attempting the Master-Cleanse again this coming weekend). One thing I know I did wrong was skipping the SWF. Apparently, if you eliminate adequately, the horribleness of the cleanse will pass quicker.