I learned to do away with the fast food by making sure I have plenty of nutritious foods at work or in the car if I am traveling. With a bit of experimentation shopping this is not that hard to do (and I eat mostly organic and can still manage it).
Fresh fruits and veggies are great. As are things such as individual foil packets of tuna or salmon... Peter Rabbit organic pouches of fruit sauce (my favorites are apple/grape and apple/peach but there are a lot of varieties). Pre-cooked brown rice in individual microwavable servings. These are just a few ideas but there are lots more you can find.