I read on the website of the trainer who worked with the actors/stuntmen in 300 that your health is 70% diet, 30%. exercise. So it is pretty important to watch what you eat, becuase you can only make up for some of it with exercise.
I don't think anyone has suggested you find a new job, but depending on your circumstances, it may be much easier for you to remove yourself from the temptation. It just depends on your level of desire.
Anything that is worth doing requires discipline from within. You will never accomplish your goals if you don't set your will.
Getting an accountability partner is a great way to watch what you eat. It's basically like weight watchers, only insead of a group it's just one other person. You can keep a journal of your eating habits every day, and then you have to tell your partner all the bad stuff you ate every week.
Find someone who is already on the right track (as far as their diet goes) and willing to help, and you'll see some amazing change, if you really want to be healthier.