I love Planners, To-Do Lists and Diaries. For some reason, I get a kick out of ticking off those little boxes after accomplishing a task or scheduled activity, and it brings me priceless peace at night to see a fully-checked-off list when I wind down with my diary to (over)think the day that was. It also gives me a chance to see my inefficiencies and (try to) correct those the next day.