I have a busy work schedule, getting only about 3 hours per day free for myself per day. Around work, there's not a whole lot of interesting choices to eat for lunch, and at dinner time, the closest thing to 'restaurants' around me are a really horrible chicken place or ready-made meals from a close-by supermarket. If I wanted to eat my own home-made food, it would take up a significant amount of my 3 hours deciding what to eat, preparing the food and clean up afterwards, so it would be likely that in a situation where I'm choosing between a healthy meal and sacrificing my leisure time, and a quick meal from that awful fried chicken place, I would probably go for the latter pretty often.
Instead, I have settled on a method that changes my choices. On Sunday, I would do my weekly grocery shopping and devise a nutrition plan. With free software like MyFitnessPal, which has a large database of foods, it's easy to decide on Sunday what I would eat for the rest of the week, stay within a calorie target, and ensure each nutrient is adequately catered for. If I'm feeling particularly lazy, I can simply copy days from before - once you've done a full week's planning, you can switch days around for variety if you still don't feel like you've had enough of it. This turns 10 decision points throughout the workweek into 1. It's much harder to consciously decide to go against a healthy meal you decided yourself once the decision has already been made - your mental investment into this choice makes it harder to throw away.
Nonetheless, there's still a good chance that I just couldn't be bothered with all the washing up and the chopping involved. This is where the prep-work comes in. I've bought an inexpensive food vacuum system that seals food in airtight, vacuumed bags. This allows me to prepare all the food beforehand, and keep them fresh for the entire week. When it comes to cooking time, I simply open up the bag and drop its contents into a pan. Preparing beforehand also saves time on washing up - instead of washing the chopping board and knife 5 times a week, I cut it down to 1.
(Some mixed bell peppers & spring onions to be opened on Wednesday evening)
With this system, I've consistently cooked my own meals for both lunch and dinner. The method preserves my choice over my meals. I can eat what I like and be creative about what I want to eat, which differs from prepared ingredient box delivery solutions on offer. It is also healthy - I would have planned my entire nutritional intake for the week, and for the vast majority of the time, I have no trouble sticking to it. Lastly, it is also cost-effective. Cooking your own food is always going to be the least expensive option.
The essense of how this works for me is that it makes the healthy decision the default decision that has to be made on the spot. It's hard to choose healthy when it involves extra brain power and extra effort. By making the decision beforehand, suddenly going for unhealthy requires more effort. Why make the trek to buy the awful chicken or the ready meals if I have everything I need here already? I can just put it in the pan and eat!