I ended up cutting out a lot of caffeinated sodas (which eventually became most sodas) and tea from my diet for health issues - now I find that I'm more likely to grab a bottle of water than a soda anyways.
I think the key is keep it away from you.
Don't buy it anymore when you go grocery shopping, keep it out of your house. Try to make yourself get water when you're at a restaurant. And you can give yourself a treat every once in awhile, just not all the time.
Really, just get rid of it from your house and you're much less likely to drink it.
After awhile, it just becomes second nature.