Just keep going! No diet that claims you will lose that much weight/size in such a short amount of time is worth your time. It takes hard work and patience, and there will be "mistakes" but we learn from them and keep going. It WILL BE worth it.
Create first a good habit, next push on to create a good lifestyle. I do not know how accurate 21 days and 90 days are in terms of creating a habit and lifestyle respectively. But I do agre. (Nice Try Health Fitness)
In my I kept hearing frm my frnds & fam: "why do u buy all these expensive ORGANIC food & drinks? they're probably not all that much healthier. Well, I'm proud to say I'm healthier & much younger looking than my age.