You have to want to eat healthy and set the appropriate mindset. For example instead to order that fastfood crap just eat some simple raw, "spartan" food(bananas, boiled meat or even fried meat etc). I have some good experience with that working long hours on my own startup(s) without distractions.
I doubt you don't have 30 minutes to "prepare" your dinner. After all you don't really prepare much. Just boil or fry whatever raw food you have.
Of course convincing kids to eat not very tasty food may be a different story but it's doable because I've seen that too.
At some point you may start to appreciate the simple food and hate when the chefs put you sugar and all kinds of "flavours" in your food.