I really admire those who follow the Newcastle diet - it is amazing to have the power to put yourself through that!
For me, a large part of making successful food choices is (1) forward planning and (2) scheduled cheats.
I think it is true whatever diet you choose (LCHF, low calorie, low fat, Newcastle, Slimming World etc.), but for me on LCHF, I avoid temptation by planning ahead as much as possible.
(a) I always have suitable snacks to hand so that I reach for a Babybel or a handful of nuts instead of that bag of Malteasers.
(b) I try as much as possible to take a packed lunch to work so I actively avoid a situation where I have to go out to buy my lunch and I am hungry and faced with bad choices.
(c) When I think I am hungry and it is between meals, I have a large glass of water then wait 10 minutes. I read somewhere that often we confuse thirst with hunger so, I check first if I am truly hungry!
(d) I seek alternatives to food to combat boredom - read a few pages of a book, buy and read a magazine, go for a walk, have a bubble bath, try out a new "look" with my hair/make up, online window shopping, reading and posting on an online forum etc. (the magazine one works best for me as buying a trashy magazine costs as much as a chocolate bar and I count it as a "treat" is it's not something I do often!)
(e) I plan a cheat meal once a week. If on a Monday I really need some cake then I remind myself that on Friday I am planning on going out to eat. It helps to have something to look forward to! (Although interestingly, if I have been "good" for a week, I tend to forgo my cheat meal as I don't want to ruin a winning streak!!)
(f) Reward yourself for good behaviour - you deserve it!