How do you prevent yourself from using the vending machine at work?

I never got anything from the vending machine! I think the prices are too high and I could buy those products for a fraction of the price in a supermarket.
I do use the beverage machine, though, the one that makes coffees, cappuccinos and hot chocolates. I'm always getting something there, and the way I find to prevent myself from doing that is by not having coins and low value paper money so that I don't have a way to pay for them. But I do allow myself to get something from there at least a couple times a week.

 

I got hooked on these at one of my former jobs. Not only did they have the usual non perishable stuff like chips and cookies, but they also had several refrigerated machines with all kinds of sandwiches in them. Those were my downfall - especially in the mornings. When I would get to work early and go get my morning coffee, I could not resist getting this Sausage Croissant sandwich. It came with cheddar cheese and yellow mustard. Especially on days where I didn't get much sleep or was hungover from the night before, that thing would totally hit the spot. I always managed to have just enough change in my pockets or desk to get one too, lol.

Aside from not walking past the machines as much as possible, try keeping stuff like canned nuts at your desk. Or perhaps some homemade hummus and carrots/celery in the fridge to snack on when you get the munchies. Some people even bring hard boiled eggs to work. I make my own black bean dip that I like to snack on with carrots - just some canned black beans drained, mixed with a spicy jarred salsa and a little cumin and olive oil in my blender for a bit, until smooth. Oscar Meyer also sells these new "protein packs" which you could easily make yourself. They are just a collection of diced turkey, some peanuts, and some diced cheese.