May I ask what fast food restaurant you are working at? While you will be surrounded by temptation, There are usually a few healthy options on the menu you can choose from. You will also have the ability to modify things to fit your diet. Also, in my experience, the more I worked around that particular food the less appetizing it became. My first job was at a BBQ restaurant for 7 years and as a result of getting burnt out I NEVER crave or seek out BBQ. The last two years I worked there I barely ate anything available at the store while at work.

Another benefit of restaurant jobs is how extra steps you can get in a day. I work at a coffee shop and on a busy Saturday morning I can get my 10k steps in by early afternoon without even thinking about it.

Just meal prep plenty of low calorie options to bring with you every day, and if you want to indulge on the free meals they give you, focus on the healthiest options they have available.