I used to always go on one big grocery store run on Sunday afternoons. I'd make a list for the week and get all the produce I thought I'd need for all my meals and snacks. Having all those fruits and veggies around did inspire me to eat them, but by the end of the week everything started to wilt and lose its firmness (and its appeal). That's because the vitamins and minerals in produce start to diminish as soon as they are harvested. So if they stay in your fridge too long, the less healthy they are for you. Not to mention they're also less flavorful, which means they'll be less tempting to eat.
Instead of going on one weekly grocery store shopping spree, try to spread out your shopping and go two or three times a week. I know this will take more time out of your busy schedule, but if eating healthy is important to you then you'll reap the benefits.