Don't tell anyone but I don't really "PLAN"!
I do my grocery shopping on Sundays without a list. I have a running tally in my head of the odd things that I need and I know how many of a certain food group that I'll normally eat so I just wing it. For instance, I know that I normally eat 3 servings of fruit a day so I just make sure that I have 20 or so servings of fruit in my cart. I buy a big selection of salad fixings and a few servings of veggies for steaming. I buy a few cuts of lean meat. Certain things I know I need every week like a large tub of plain yogurt, etc.
When I get home I invest some time in preparation: cutting up veggies, putting snacks into individual serving bags, etc. , packaging meat into individual servings and freezing it, etc.
Breakfast is some kind of hot cereal and a fruit. Mid morning snack is yogurt, usually with berries. Lunch is a veggie soup or salad, raw veggies, a piece of cheese and some fruit. Not much to think about there. Dinner is whatever I decide when I'm driving home, based on what caught my fancy that week at the grocery store. Every once in while, some wild craving will strike me (the other day it was steamed spinach) so I just stop at the store on the way home.
For me, planning ahead just doesn't seem to work out. Something will come up and I'll end up grabbing dinner out or I'll be too tired one night to prepare an elaborate dinner or I'll have planned something quick and simple and I'll be in the mood to cook.
For exercise, I hit the gym on the way home from work. My usual intention is to go on Monday, Wednesday and then again on Saturday morning but again, I keep my work out clothes in the car all the time, so I can decide on the way home. On days I don't go to the gym, I usually do something at home: hop on the treadmill, do some weights or squeeze in a yoga workout.
I guess I do plan a little, just not very far ahead. I don't really think of it as spending time thinking about maintenance or obsessing about food because I 'plan' the rest of my daily life this way too, so why not what I eat and when I exercise?