When I was in grade school, I used to to carry a large water jug to school everyday. Inside the container was either iced tea or orange juice with a lot of ice. This habit changed when I was in high school: I replaced the sugary treat with plain water. I then used part of my lunch money to buy drinks when I needed a sugar rush. However, I graduated and soon went to college. Carrying something as bulky as a water jug was inconvenient, so I turned to water dispensers and buying drinks in the cafeteria.
I then realized that I was spending TOO much money on drinks when I got thirsty. Thus, just recently, I have begun toting around a water bottle. It's much smaller, and I can refill the contents with the water dispensers at zero cost. Because of this new habit, I have reduced my drink bill by 50% to 70%.
Looking back, I know I'd save 100% if I could stop myself from buying sweet treats, but I can't...
At least water bottles are easy on my pocket, and the environment (think of all the plastic I'm not wasting :)).