When you're sticking to a budget, it's important to make time once in a while to review your spending habits. Sometimes, we can spot patterns of spending that are easier to reduce if we make the act of spending a little more difficult.
Financial blog The Simple Dollar points out that it's easy to overlook certain types of purchases even when you're keeping a close eye on your budget. Things like saved credit card information and one-click spending can certainly be convenient, but they can also be a little too tempting and even habit-forming. Speaking specifically about how easy it is to buy Kindle books and forget to track the purchases:
I'm trying to break a spending habit and the easiest way to do that is to eliminate that "path of least resistance." If I make it much more difficult to buy a Kindle book, then it's going to be much easier to establish a pattern of not buying such books.
Removing these conveniences doesn't prevent you from making the purchase, of course. It just puts up a little road block that makes you think twice. And the change doesn't have to be permanent. You're really just after some time to break a habit.