MixedNuts, I'm in a similar position, though perhaps less severely, and more intermittently. I've been diagnosed with bipolar, though I've had difficulty taking my meds. At this point in my life, I'm being supported almost entirely by a network of family, friends, and associates that is working hard to help me be a real person and getting very little in return.

I have one book that has helped me tremendously, "The Depression Cure", by Dr. Ilardi. He claims that depression-spectrum disorders are primarily caused by lifestyle, and that almost everyone can benefit from simple changes. As any book--especially a self-help book---it ought to be read skeptically, and it doesn't introduce any ideas that can't be found in modern psychological research. Rather, it aggregates what in Ilardi's opinion are the most important: exercise works more effectively than SSRIs, etc.

If you really want a copy, and you really can't get one yourself, I will send you one if you can send me your address. It helped me that much. Which is not to say that I am problem free. Still, a 40% reduction in problem behavior, after 6 months, with increasing rather than decreasing results, is a huge deal for me.

Rather, I want to give you your "one trick". It is the easiest rather than the most effective; but it has an immediate effect, which helped me implement the others. Morning sunlight. I don't know where you live; I live in a place where I can comfortably sit outside in the morning even this time of year. Get up as soon as you can after waking, and wake as early in the day as you would ideally like to. Walk around, sit, or lie down in the brightest area outside for half an hour. You can go read studies on why this works, or that debate its efficacy, but for me it helps.

I realize that your post didn't say anything about depression; just lack of willpower. For me, they were tightly intertwined, and they might not be for you. Please try it anyway.