And a first aid kit is probably good too, if you don't already have one. I've used mine several times. Reflective roadside signs for if you need help, too. And jumper cables, if you don't already have those for some reason.
Honestly, I just carry a first aid kit, small folding shovel, space blanket (with blaze orange outside, so it is good for catching attention in emergencies), fleece blanket, and jumper cables. Out of those, I have used the first aid kit, fleece blanket, and jumper cables. Don't let us freak you out by listing stuff to get, odds are you won't need it. I would still get it, though.
Trail mix actually could be important to carry around on your person during the day, depending on what your job is. Your body burns calories like crazy when you are in the cold, especially when you are working in the cold. If you want to save money, you can buy a bunch of peanuts, cashews, raisins, dried cranberries, M&Ms, pretzels, and anything similar to that, mix it up in a big bowl, and fill ziploc bags with it. Just keep water with you too, it can be really dry and salty.
Man, who knew that what I learned on school hikes would actually end up being useful one day?