I go to Sprouts--basically a less expensive version of Whole Foods. I stay out of regular grocery stores, that way I am not tempted by their Pringles and Hershey bars. There is still junk to be had, but it is less junky.
As far as the drive-thrus are concerned, you just have to decide that food is poison. Like, really get it through your head that you are killing yourself by eating that junk. Read/watch whatever you have to to make it sink in. I used to be a drive-thru junkie. Now, my fast food is a salad at Chipotle. I am not strict Primal, by any means, but I won't touch another McDonald's french fry -- and I LOVE those things. LOVE 'EM!
I don't really know when the shift came for me, I just know that one day I was convinced, really convinced, that fast food was toxic, and I haven't been into one of those places since. It's been about 4 months now.