Easiest solution: Don't buy junk food.
If it's not in your kitchen, you can't eat it. I spend about 80 bucks a week, most of it on fruits and vegetables which I force myself to eat. Another tip is to buy enough food to satisfy all your meals for the week. If you don't have enough food in your kitchen then you will go to places like pizza nova and BK. I say this because I ran out of food yesterday since I was going home for the long weekend, so I had to eat pizza nova for dinner (which proved to not be enough) then went to BK haha. But I worked out yesterday and ran this morning so its justified :P