Be careful directing energy. It has unexpected consequences, always. Not always bad ones, but you can't predict everything that happens, so there will always be something unexpected packaged into your actions.
People who are very, very energetic often surprise us by becoming thoroughly lethargic at some tasks. I'm convinced that that's because most very, very energetic people don't have more energy than the rest of us. They're just good at directing it toward activities that bring them vitality, life and happiness. They learn to love their energy, and so they continue to direct it.
Most people don't. They're used to their actions turning back on them, snake-like. They're used to doing things for (they believe) their own benefit, and seeing it turned against them immediately. Those are people who kill off the flow of their own energy out of self-defense. They are in the vast, vast majority.
So somebody who is usually energetic and becomes lethargic is, to quote papertygre, procrastinating out of self-defense. Somebody enlightened enough to understand what nourishes them, what makes them happy, but not so enlightened as to entirely avoid self-stifling (is there anybody who avoids it entirely?)... That's the kind of person who will utterly fail through lack of effort on a project that doesn't appear difficult to the rest of us, certainly not beyond their abilities.
This is very common. I'm convinced that it's especially common in creative professions - artists, writers and programmers all come strongly to mind. Writer's Block seems to often be caused by it.
I know some of the foolish and common reasons for it. Among writers, for instance, there's a sort of superstition that you've only got so many ideas, and when they're used up, they're used up. That's balderdash, of course, but it's a common enough belief. Creativity, instead, works like muscles -- the more you use it, the better you get at it. And there are easily as many books left to be written as have been written so far. We're not going to run out of topics in my lifetime, not by a long shot. The same applies to artists, who also tend to share this superstition.
Programmers seem especially bound by perfectionism (not that artists and writers don't have the same problem too). "The best is the enemy of the good". Here's another way to look at that problem: "I feel bad if I produce something and it could have been better". When we feel bad, we start stifling energy. So a lack of perfectionism, to a perfectionist, means producing *lots* of crap, which causes them to massively self-stifle. Amusingly enough, that's one *isn't* my problem.
So tell me, if you've read this far: what causes you to stifle yourself? What's your foolish superstition that makes you dam up your natural flow of energy? Say it, because somebody out there shares it, and they may be reading right now.