The decisions you take when processing tasks help to eliminate the ambiguities which trigger cognitive dissonance. In particular, it will give you a sense of completion. You can trust that you've made an appropriate decision about every task, and reduced the problem of conflicting priorities. The "to-do" lists means you'll recall deferred tasks at the right time, which gives you the freedom to forget about tasks you've processed. This system of projecting deferred tasks gives you more control over when you decide to work, allowing you to be proactive about the most important things to work on. Beyond this, the process of cutting out the rubbish you've captured and ticking off the immediate actions feels good. These ticks offer a sense of progression which makes the habit, though it requires some discipline at first, "sticky" and easy to maintain.