Since you work in a grocery store, you may be able to get a discount on the food you buy there. However that works out, working in the grocery store will be an advantage. You can take time on your break to really look at some food items and compare their nutritional values. You can bring fresh vegetables and fruits home and make it a habit.
Going to college means time spent studying, which is a sedentary activity. Even more important to make walking a habit. Is there some early morning or late evening walking group in your town? You can call the local Y (even better, join, and get active there) and ask if they know of any walking groups. You could check a place like craigslist and see if anyone is looking for an exercise or walking buddy. You could even post such a request yourself. Try to make moving more part of your life.
I say that and yet, I have a difficult time doing it myself. Maybe a time management problem for me!