I find that you have to feel a bit hungry at times to do it. Your hunger is your bodies way of maintaining your weight. Unfortunately you can also teach it you need too much food, if you've gained weight. The art of distraction is valuable. Or drinking another glass of water.
If you are petite i think this also gives you less room for treats. You really have to think about what you are eating and be honest with your self about it.
I think this is why a lot of people on diets do actually fail - because they aren't honest with themselves and aren't disciplined about it
Also do think about how covid may have created a change in lifestyle that you hadn't fully realised. For example ive noticed how not doing the school run over the summer has reduced my exercise far more than i realised and covid allowed me to develop a few bad habits.
Portion size. People really do think that bigger portions are 'normal'. Slowly cutting back is useful. A lot of people think that what they are eating is healthy but don't realise they are eating double size portions unwittingly. You can't get your head around this until you start adding it up and looking at quantity / calorie content. It can be an eye opener.
Also lifestyle changes have to be sustainable. Its no good ditching the reeses for a while to lose the weight and then starting it again. You have to be conscious of how they are problematic. By all means have one occasionally but be aware of how occasionally becomes a habit again.
Personally i find crisps and chocolate in the house the issue. If they are there its too easy just to go get one in a moment of weakness. If i have to have them in the house, ive found putting them upstairs and out of the kitchen is a good way not to automatically take one, but to enforce a moment where you have to make a conscious decision to have one and think about going upstairs. The effort of having to go out of your way to get one and having that break in behaviour pattern makes it easier to go 'do i really need/want one?'.
I've always done this previously and ive slack off during the past year or so and put on an extra stone. This is a lot for me so im now finding im fighting it which is hard. If you do want a treat build it into your calories for the day. Not because you deserve a reward because 'youve been good this week' - (again bad habit and psychology association). Have them because you have calories available to do so.
No easy fix i think is the issue and people aren't honest about it - especially with themselves. Once you have the knowledge and better habits you can stop being so religious about it because you just 'know it'.
Finally middle age spread due to hormones etc is less of a thing before age 65 than people realise. Its actually small unnoticed changes in lifestyle which creep in during middle age when we are comfy that are more to blame. Theres new research on this and its surprised a few. Also research that shows significant weight gain between 18 and 35 is an indicator of problems further down the line - again which owe more to lifestyle than other causes. Once you get past 35, it seems if you have had good habits up to that point you keep them going forward and have less weight issues.
Of course this is apparently controversial. Unfortunately.