I'm a little behind on this post but just thought I'd contribute my two cents.
I use to drink a three liter bottle of mountain dew everyday, as well as cans of coke, jugs of oj, chocolate milk, basically anything with sugar or caffeine. After stopping I was able to achieve a loss of 110 lbs, I went from 345 to 235. I'm not implying this was all due to modifying my beverage intake but it sure helped.

First, let me say that it is not easy to stop and although cold turkey works for some, it also typically is an over simplification of the process. In order to quit, the motivation has to be tangible and a routine has to be established. Many people have hinted that they had an underlying motivational tool, such as health. However, simply stating health as a reason or that you don't want to die may be to intangible for some. Your goal may be more achievable if you sit down, write out all the reasons why you want to quit, in significant detail and begin to associate them with your everyday routine, such as referencing them each morning. You might also consider writing down reasons for why you may fail and seeing if you can address those reasons. If you don't want to workout, why don't you want to workout? Typical response, I don't have time. Then, you need to prepare a plan to give yourself 30 minutes or an hour each day, remember, something is better than nothing.

Additionally, you need to substitute something for the soda. If you workout, during and following your workout, remember how good the water tastes, how refreshing, amazing and clean.

The biggest struggle is going to be your down time. Try to add in things like Trevi or Perrier, you can get them in several different flavors. Don't get stuck on one thing though and vary up your drink choice, just make sure it lacks sugar or sweetener,or you will just be trading one vice for another. Keep associating your goal and your reasoning for that goal with the experience. When you get hit with a major craving do something stimulating, do not go on reddit or watch TV. Instead go for a walk or go to the gym or contact a friend and talk about anything.

Its going to suck, you are going to have cravings and headaches and be irritated and short tempered. Try to remember it's only temporary and those around you are not doing "the thing" to specifically annoy you. Take a breath, walk away, think and then come back. It will make a huge difference for how you deal with people, as well as your cravings.