Healthy eating goes a long way.
As far as cooking goes, the real task is buying the right foods at the grocery store. Never go to the store hungry. If you only buy healthy foods, you can only eat healthy foods, at home that is.
You'll just have to face the arduous endeavor of resisting the urge to eat fast food.
Once you go a long period without eating fast food, you probably get a sour taste in your mouth at the thought of it.