A (somewhat) foolproof system
I always go grocery shopping on Friday and I always bring a shopping list with me. You think it's the list of the food items I need? Not at all. See, I record all the good and the bad things that happen to me during the week, and buy my foodstuffs accordingly.
How does this work? Let's say I finish a difficult work assignment on time. That calls for some red wine, a little bit of cheese and a couple of chocolate bars. Or maybe I don't miss any workouts all week. In that case, I'm buying a lot fruits, veggies, whole grains, loads and loads of health foods. Even celery. Though I think we all agree, no one in their right mind likes to eat celery. If I met a cute guy during the week, I will buy no chips and less ice cream than usual. This guy could easily turn out to be the one, so the fewer junk food I'll buy now, the better I'll look for our wedding later. Just kidding!
If, for instance, I'm having a rough week, my shopping basket reflects that, too. Most of the items in it will be low in nutrients but high in calories. I will buy fewer ingredients for cooking and more prepackaged meals. I never have enough energy to cook when things are not going ok. Luckily, that doesn't happen very often – maybe just several weeks per year. And frankly, when it does, I usually send my Mom for groceries. She's perfect at it!