Jerry Seinfeld once gave a great motivational tip on how to stick to something. When he was a fledgling comic he would sometimes feel making little progress, but knew that he had to stick to writing jokes every day, day-in day-out.
To spur himself on he took a big year-long calendar and would mark a big red cross in the day when he would write. Each consecutive day that he added would create a longer chain that was visually motivating.
The key was not to break the chain.
You can apply this easily to quitting coffee. Each day that you don’t have a coffee can spur you on and carry towards being completely caffeine-free. You certainly won’t need to have a year-long calendar either since you should be able to break the addiction and habit within a month or so.
Even if you drop a day you’ll be able to see you much you’ve previously achieved to motivate you to try again.