you're not hurting yourself because you weren't really fasting since it was only the first day. If you were to do this after day 3 you would be hurting... physically, in pain. It's hard on your digestive system to go from resting and empty to processing a complex food... I don't think that would cause damage to the body {not 100% sure tho}.. it would just make you feel B A D.
I know you can do this. It is actually alot easier than you think. Every time you feel like breaking drink your lemonade. Do other indulging things for yourself too.
You can do it! Just make up your mind that you're going to do the whole thing. :) Happy cleansing.