I have a new theory. Activation energy (not my own theory). It's like the inertia theory. It takes awhile to get going, but once you do, you stay there. And when you're lazy, you stay there. That's inertia.
Activation energy is the energy required for a chemical reaction to go. The reaction may be favorable but the rate may be so slow that it never goes. There's an initial hump that it has to get over to go to completion. An enzyme can come in and lower the amount of energy required for the reaction to take off. This is where real-life comes in. When I'm starting something new, it takes forever. I have to figure out what I'm doing, procrastinate, try it a few times and mess up; then, all of a sudden, it takes off. It gets easier and easier to do it and then I start seeing results. Take working out for example, running in particular. When you're out of shape, it takes a ton of energy to get up the guts to do it. It hurts, you get stitches, you can't breathe, your feet hurt, your sore for days afterwards. It's like this for a week or two, then all of a sudden, it gets easier. You've gotten over that activation energy hump, and now it takes less energy to go out there and do it. It's enjoyable, rewarding, and you look forward to it.
So the moral of the story? It takes a lot of energy to get something started, but it does get easier.