Pre op diet has been a struggle for me at times too. Especially like when the other people in my house can have the food I know I shouldn't eat, but love anyway. I'm grateful it's not a terribly long time til my surgery and I just won't be interested in that kind of food. I just have to keep reminding myself why I chose this in the first place (which honestly isn't that hard).
I got into a lot of bad behaviors with food, so I'm having to re-learn healthy eating habits. It's a little hard to imagine life without some foods, but I know it will be better for me in the long run. You'll learn to adjust, it's just hard to do after a lifetime of living a certain way.