I have tried more productivity systems and tools than could possibly be productive. Stephen Covey’s 7 Habits are deservedly legendary, and I’m better for every habit I’m able to employ. David Allen’s Getting Things Done (GTD) methodology was even more helpful for me, especially because it seems to hone the best of Covey’s principles to a more elegant simplicity. But both of their complete proprietary systems proved too much for me to maintain long-term.