how do you avoid buying junk food when everyone at work eats it every day?

how do you avoid eating junk food if most people at work eat it every day? Im trying to avoid french fries and coffee. I love things like potato chips french fries really anything with a ton of oil truffles, its not healthy at all. I also love chineese food and they have been eating that alot too, its not just about junk food its also about things that I cant cook at home i am also avoiding eating out, i cant cook Chinese food it doesnt turn out well.