Great British Bake Off finalist and psychologist Kimberley Wilson told Metro UK that a common mistake people make when changing their diet is trying to do too much at once.
"We eat mostly out of familiarity," she says, "so it can feel like a big jump to take away familiar foods at the same time as introducing new ones."
She believes it's better to think about what healthy foods to add into your daily diet, rather than what to take out - it's a more "practical" approach.
"So, let's say you regularly eat pasta and sauce on a Monday. Instead of changing that meal entirely, try thinking about where you could add more fibre, healthy fats and vegetables," Wilson says.
"Could you switch to wholemeal pasta, or half and half? Could you add in some lentils or beans? Perhaps you could serve your pasta with a portion of trout or salmon. Or could you stir in some spinach or serve it with a side salad?
"This way, you are making the foods you currently eat more nutritious, which should make the changes easier to sustain."
Which foods actually make you feel good?
It all depends on how you look at it. A cinnamon roll from the bakery at the end of a long workday can be an instant mood boost, but so can a salad.
"Food can make us feel good in lots of ways," Wilson says.
"Just the act of eating can release chemicals in the brain that elevate mood and certain foods, like sugar, can give us a buzz. Some nostalgic foods can elicit happy memories.
"We can also use food to distract ourselves from unpleasant feelings, but these effects are typically short-term and may have other negative consequences.
"For long-term improved mood, we need to think about what nutrients our brains need to function well and how we can provide those on a consistent basis.
"A healthy brain needs essential fats, micronutrients (vitamins and minerals), fibre and water."
So don't beat yourself up next time you get a craving for chocolate.
Rather, think about where you can add in healthy foods that will help your diet in the long term.
Whether it's adding some fruit to your breakfast in the morning or switching to wholemeal pasta, there are countless small changes you can make that will help lift your mood in the long run.