Here is what I do when I need to be particularly organized and productive. I call it a to-done list. (I'm lazy and probably have ADHD, so I never sustain. But whenever I do this it feels great, and it is never hard to start it up again when I get motivated.)
I start with a small list of things that I absolutely have to do, in roughly the order that I plan to tackle them. Put that in a plain text file. Write the date below that list.
Take the bottom task, break it up into subtasks, recursively, until I've got a task I can work on right now. Do it. Move it down off the list to the date. If I get blocked on that one, add the blocker below the task and pick another task. Continue all day.
The next day I start by putting that day's date above the old date, and then continue again.
The keys to this are the following:
1. I ONLY include things that I HAVE to do. (Adding all of the, "It would be good to some day" or "I'd like to" leads to depression as described by Jeff.)
2. Items are SPECIFIC and SMALL. The goal is to constantly move them off the list into done.
3. Only include CURRENT stuff. If there is a project that is intended for 3 months from now, it does not go on the list.
This list serves 2 purposes. The bit at the top is pretty much a LIFO stack (I add at the bottom, take off from near the bottom) of what I am currently working on. So it is the whole, "I need to do Y in order to do X, be sure I get back to X eventually." And the long list at the bottom is a log of how much I got done, which makes me feel good.
If you try this, be aware that a quickly growing top section is proof that you're doing it wrong. Go through the top bit and ruthlessly prune off everything that doesn't need to be there. Yes, I know that some people feel good about taking a list of high level tasks and breaking it up right away to get organized. But really, this makes the list explode, and you won't do as good a job of exploding it out as you will when you are closer to actually doing that item.
The rule of thumb is, if you have trouble scrolling through the todo to the already done, the todo is clearly too long.