I grew up on Kraft Mac and Cheese, Hamburger Helper, Mountain Dew, frozen dinners, and vending machine food... and then married a vegetarian health nut.
Over the last 8 years, I've slowly, slowly embraced the idea of a whole foods lifestyle. It certainly wasn't overnight.
I thought the stuff he ate was bland and gross. Now I'll happily join him for lunch at the local vegan cafe, which most of my coworkers shun for it's bland, gross food.
(not that I'm vegan or veggie, I still eat meat, I just enjoy vegan and veggie food now, too!)
For me, focusing on "whole foods", especially this time around as I lose weight, has meant avoiding "diet foods". I don't eat the 100 calorie snack packs anymore, or the Lean Cuisines I lived off of the last time I seriously tried to lose weight back in 2003. I avoid Nutrasweet and Splenda, using Stevia extract when I need something sweet to put in my oatmeal, and just in general avoid any food that's been forced into low-fatness for the sake of marketing to the diet crowd. It's not an "elitist" thing, it's just that I've slowly started to prefer the whole foods over the easy quick foods in the last couple of years.
Reading a bunch of articles by Michael Pollan didn't hurt, either, he totally changed the way I looked at corn, high fructose corn syrup, and meat that was fed corn, that's for sure. Eating "whole" foods has been an easy way for me to reduce the amount of corn and soy I eat, and get more variety from lots of different grains/plants, the way we were designed to.