Getting Things Done: The Art of Stress-Free Productivity by David Allen is the singular most influential productivity book that I have ever read. The methodology that is laid out provides me with a framework to easily track all of my current obligations, remind myself of projects that I may want to do someday, and most importantly decide what is the best thing for me to be doing at any given moment.

GTD®, as it is known, recommends certain behaviors to accomplish this organizational wizardry. The five stages of GTD® are Capture, Clarify, Organize, Reflect, and Engage. Each stage identifies certain steps you must follow in order to successfully implement that part of the process. Some steps are simple and straightforward while others are more challenging and complex.