Michael Neill has a wonderful discussion somewhere in one of his books (and I've heard him talk about it on his radio show) about inertia. You know, an object in motion tends to stay in motion; and one that is at rest tends to stay at rest. (And I'm sure if there were a physicist in the audience, she'd have some much more complicated revision of that "law" we got told in school, but I'm going to hang onto my old ideas for now, since I'm actually more interested in their metaphorical application here to personal development.)
Anyway, his idea is that many of the difficulties we attribute to anxiety, fear, or procrastination are really just the force of inertia. If you're not actively working on a project, you are resting, inert, and not moving -- not because you're stupid or lazy, but because it's an energetic principle of this world. And, correspondingly, once you can take a little tiny step towards whatever project or goal you'd like to move towards, then the next little step gets easier. But sometimes you need a shove or some assistance in the right direction. And that's the booster rocket -- once out of the Earth's atmosphere, the spacecraft no longer needs all those rockets it needs at first to get off the ground.
For myself, I know that inertia is a very real force-- and something I struggle against, because once in the grip of it, I can't always see that that's what's going on. Rest is something we all need, in the sense of relaxation, reflection, pause. But there's some very fine line between that sort of rest (what I needed right when I came back from my intense conference and research trip combo) and the rest of inertia, the rest that feels like you can't quite get out of the mudpit. (Being prone to depression doesn't help things, since when I feel inertia then I start to wonder if it's the greys starting up again.)
Luckily, I was listening to some old podcasts on my mp3 player and heard the one about inertia again and realized aha! that's what my problem has been for the past week or so. So I set myself a clearly defined intellectual task, and made myself accountable to someone else about it (a friend who I had to email afterwards) and made sure I had quality caffeine . . . and what d'ya know, inertia got kicked to the curb. At least for a few days I hope. What's tough is that seems so obvious. Do work, get involved in work, get excited about it again. But sometimes it's the getting started, and re-started, and re-started that is the hard part. At least for me.