I've dropped soda entirely by substituting green tea. I bought a kilogram of it loose, and brew it with a microwave and two mason jars (put a pinch in a quart-sized jar, microwave for 3:30, pour through strainer into second jar).
I've quit caffeine outright two or three times beforehand, but relapsed for trivial reasons.
I love drinking tea, white and green mostly, and I never crave coffee or soda. I cold brew white tea in a large diffusion jug I got off amazon overnight in the refrigerator and then I have a ton of tea for the next day or even a few days afterward. The cold brewed tea is so refreshing and delicious. I highly recommend trying it out.
This is the public group instrumental rationality diary for December 16-31.
Thanks to cata for starting the Group Rationality Diary posts, and to commenters for participating.
Immediate past diary: December 1-15
Rationality diaries archive