[ryanstorm]

Another +1 for journal here. Specifically, the bullet journal: http://bulletjournal.com/get-started/

It's very modular, so you can do whatever you want with it. But I write a daily to-do list and also use it to keep track of longer term tasks and goals.

I have used it for 3 years now, have filled up two moleskin-type journals, and my SO and I are convinced that this is the single best thing we've done to improve ourselves.