Bad foodaholic

I really love bad food. By bad food I mean the food that tastes the best and requires little to no effort to prepare and I particularly love the sweet bad food. The problem I have is that I believe it is bad food. I believe we are what we eat and that these kinds of food are bad for my mental and physical health. And so I face an inner battle between loving these foods, but knowing they are not good for me. I don't think these foods are bad for an occasional treat if you are well and healthy, but we are far from well and healthy.
I just can't get the motivation or will power to eat as well as I should. I stick to a restricted diet because if I didn't I would cause my son pain, but apart from withholding the foods he's intolerant to I eat pretty badly.
I have been pondering over why I find it so hard to eat as healthy as I need to, despite believing absolutely that it's right. It's come down to these reasons:
1) My mind set. Right now I look on a healthy diet as restrictive and I long for the day I can eat cake, pizza, chocolate and burgers again. If we were healthy now I would eat these things everyday, my mindset is still the same as it ever has been.
2) The effort. Eating healthily requires forward planning, researching, lots of preparation and practise in making all these completely new dishes. I have barely enough energy to look after myself and the two boys, let alone planning and preparing meals that I know nothing about.
Which leads me onto the final reason
3) Lack of knowledge. I have no idea about what foods do and what they are good for. There is so much to learn about each food that I have found through my research for baby, and the hours I have spent has shown me that there is far too much for my poor baby/CFS brain to take in.

I have eaten some lovely healthy foods, I have been shown that it can be easy if you know how, I have even been given a kick start. However, in order for me to be successful then all three reasons need to be changed. I'm hoping that recognising my failings will enable me to know what I'm working with to make the necessary changes.
Why oh why does bad food have to taste so good!