Over the course of a year at work, I figure I used 188 disposable spoons, forks, and cups. This is based on using one each per day, 4 days per week, 47 weeks a year (allowing for vacation and sick time). What a waste! I finally figured out that I could bring a set of mismatched silverware and a Tupperware tumbler from home and wash them in the kitchen in the break room.
This is one of those uber-obvious things that took me a while to figure out. But, it is a good example of how changing small habits can have large effects over time.