You know that moment - when you are slightly tired, stressed or bored and you think - oh I might as well eat that cake/biscuit/brownie - it will pick me up. You still go for it - despite your decision to eat more healthily, despite your decision to cut down on sugar, despite knowing it is not optimal for your health - but why?? There’s no immediate negative consequence of you eating that food. Basically nothing bad happens in the short term by you eating that one biscuit/piece of cake/brownie - so you can justify it thinking “I’ll eat better tomorrow” or “I’ll stop having this stuff from Monday”. Of course this isn’t an issue - it only becomes an issue if you are using that justification every day or even several times a day. Also eating that food once isn’t what makes it “bad” - it only becomes unhealthy for your body if you are choosing that food regularly. You can’t blame yourself - for choosing that short-term pleasure over the long-term health gains - but if you do want to make changes to your habits around food this is an important thing to keep in mind.
People who have a very strong short-term reason not to eat unhealthy food are much more likely to resist that sweet treat or super-processed snack. Let’s say you know it makes the pain in your joints worse or your skin always breaks out when you eat certain foods - you have a very strong short-term motivation to stay away from those foods. So what about if you don’t have that short term motivation? - you have to create a short-term motivating factor! Perhaps it involves imaging how bloated and guilty you’ll feel after eating something you don’t really want to - perhaps the short-term motivation is wanting to set a good example for your children every day ... it is just key you know that something good will come in that moment from you making the best choice for your health.
The problem with just generally making changes for our long-term health is that the goal is too vague and too far in the future to encourage us to do anything about it today. It will often only be when someone gets a diagnosis of a condition or a health scare that they make changes to their diet or lifestyle - because then there is a real, short-term and immediate threat! That’s not to say you shouldn’t enjoy a sweet treat or processed snack sometimes - it’s just that many people struggle with choosing these foods every day (when they don’t really want to)- because it is easier to just put off getting healthy until some time in the future.
So if you want the power to make healthy choices daily - make sure you have a very strong short-term motivation. Perhaps write it down somewhere you can see it regularly. In those moments you are tempted just to give in and “try again tomorrow” you can look at that motivating factor and give yourself the strength to make a better choice for your health.