Read as many posts and blogs as possible. The blogs are what really helped me. I am on day 24 and its my first fast ever and even though I ate a small salad on day 5, I feel like a million dollars and have lost 25 lbs so far. My first night I lost 7 lbs of water but now my stomach and face look like they did 10 years ago. It is worth it to fast as long as you can. With juice it makes it so much easier. I do recommend you do a few days of master cleanse because it has helped me the most. I also do master cleanse like 2 times a day still, in-between juicing. I have really gotten very hungry in the last 3 days now and I may stop at day 30. I really want to do 40 days now. I started with doing 3 days. When I realized how easy it was, I went for 7, then 10, now I'm definately going to do at least 30. 10 was a great number of days to fast because I saw a lot of improvement. Day 16 I lost like 15 pounds. Day 20 my head got so clear its not even funny. I feel so good and its so awesome. I just stumbled into this forum by accident and joined 5 days later after I read all the comments. I wish I took a picture on Day 1. I took a picture on day 5 when I already lost 11 lbs.
Anyway, good luck and make sure you read some of the people's posts that have been doing this for over 100 days. It will motivate you!