I used to have a serious sweet tooth and got really bad sugar cravings, to the point where I'd have to have a small packet of sweets or a bar or chocolate every evening, and I was the type of person who if someone gave me a big bag of haribos or a box of chocolates for my birthday I'd eat the majority of them in the space of a day
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Just over 2 months ago I cut them out of my diet, I found it difficult for the first couple of weeks but after that my sugar cravings started to go away, and I honestly don't miss sweets or chocolate anymore. I went on holiday last week, didnt eat sweets or choccy but I did have a dessert every night (I don't eat desserts normally) and it was nice to have sugary sweet puddings, but I felt satisfied and didn't crave more. So maybe if you cut sweets/chocolates out completely for a while, when/if you start eating it them again you'll be able to enjoy them as a small treat once in a while rather than eating loads in one go.
The best thing to do though to stop you eating loads at once is to just not buy loads of it - just get one small chocolate bar, not those big sharing bars or multipacks. If someone else in your house is doing the food shopping and buying chocolate, ask them to hide it and not put it in the cupboard so you won't have to see it.
About the 'rules' thing, I personally think a lifestyle change is just about being healthier in general, if you have strict rules it just becomes a diet and you may end up resenting it, plus it's difficult to fit rules in with life - social events, staying at a friends and having to eat what they have in the cupboards etc. Just try to chose healthy options, be active, tell friends/family you are trying to eat healthily but if you are in a situation where someone cooks you a meal that isn't so healthy, just watch your portion size.