So I'm usually do a ton of lurking on here but today I'm taking the plunge and posting!
Anyway, I'm terrible with sticking to a "diet" and in turn feel like I shouldn't even post here. But something that seriously benefitted me and helped me cut out the fast food that I used to know and love was learning about what goes into the fast food we eat and the way the animals are treated, how it affects local farmers, etc, etc, etc.
I'm so not going to get on a bandwagon about eating organic (because no one wants to hear that from me) but since I took the time to watch some movies (like Food Inc) and read about the differences between organic and non organic and everything that goes into it, I just quit fast food cold turkey. I never have a craving, I never even want to stop to get an iced tea from a fast food place. I only eat organic meat and fruits/veggies and it's totally helped me in my weight loss as well as the way I feel over all. Even if you don't intend on switching to organic food, it totally helps with fast food cravings.
So long story short, it sounds weird, but if you need a reason to quit processed foods and fast food, educate yourself on the way that stuff is made and it'll probably help you quit that stuff.