So if we're being honest, what is the thing most people find the most difficult with regards to fitness goals? It's the nutrition/diet itself.
In reality "Dieting" or "Clean Eating" isn't that hard, it's the way people go too extreme in comparison to what they were eating that makes it hard.
This can stem from someone having very little education about what foods are best for their goals, not having the time to prepare decent quality meals, not being in a financial situation to afford the best quality foods or even actually knowing what foods to eat but struggling with actually eating them as they don't particularly like them.
OK, first thing:
It shouldn't be looked at as "a diet", this implies a period of time with an end. The only people who should be doing this are competitive bodybuilders and athletes that need to reach a weight criteria as this change IS NOT MAINTAINABLE. Your nutrition needs to be looked at as the way you eat all the time, with opportunities to eat things that are deemed as "treats" or "cheats" and is maintainable in day to day life. You can eat ANYTHING and get/stay in shape, it's about being realistic about how much of these foods you choose to eat.
Foods shouldn't be categorised into good or bad, everything has a place. For example, the foods that would be counterproductive to someone trying to lose body fat would likely be very useful for a Tour De France competitor, this does not mean a food is good or bad. On the flip side you have foods that are nutritionally beneficial to someone trying to lose body fat that when over consumed will still put you in a calorie surplus and add body weight and hinder fat loss.
Another problem is when people start to make conscious changes to their food/nutrition intake it's often done with very little research to confirm what they're doing will help.I often see things such as people swapping Coca Cola for Fresh Orange instead or opting to eat raw carrot sticks instead of eating biscuits..... swapping sugar for sugar will not make a difference to your goals whatever they are, the only benefit would be an increase in Vitamin C intake which in all honestly you're probably consuming enough of anyway, and swapping something very tasty and calorie dense for something quite bland and near calorie free is (in many cases) going to be very unsatisfying resulting in some kind of binge.
Your food needs to be enjoyable, that's how this will work.
Do not fear Condiments, Sauces and Sodium, just don't have a bottle with every meal! Be very wary of things like creamy sauces, full fat Mayonnaise and Butter as these are very dense in calories and it would be quite easy to add an extra 200+ calories to a meal without paying much attention, this doesn't mean never have them though
Here's a few very simple ideas to try and help you with some of the above problems:
Be realistic with the takeaways and treats, everyone loves sweet foods or a pizza etc, but moderation isn't every night