I give up if I don't see or feel results within the first week.
I have been on Cohens now for over 5 weeks, and I am still going strong... I have lost just over 18kgs with loads more to go. I believe the only reason I have stuck to this is because I feel like this could be my one real big chance to lose the weight I want to lose, in a short amount of time. I also don't feel like I am missing out on anything... even though I am... I guess it is because I am eating so well, and eating decent meals.
I have given up on every other diet I have been on in the past... at the end of my first week on Cohens, I had lost 8.2kgs... that was the motivation I needed to stick with it.