A body continues in its state of rest or uniform motion unless acted upon by a net external force.
At the beginning of Chapter 1 I listed ten activities which I always find difficult to begin. I also pointed out that, although they might be difficult to start doing, once they're under way they're not so bad. Just as a car requires more 'juice' to start it than keep it ticking over, so your brain and body need more impetus to begin a task than to continue it. Ignition in all things demands a lot of energy.
What I'm saying holds good for almost any activity, and there is a good scientific reason for it:
That which is inert wishes to remain so.
That is a simplified paraphrase of Newton's first Law of Motion quoted above. So is this next sentence, its natural converse:
That which is in motion will wish to remain so.
It's easy to prove the truth of these two principles. Imagine yourself (body-weight between, say 110-160 Ib) straining to shift a boulder weighing a quarter of a ton (560 Ib), in order to get it rolling down a hill. All your muscular effort will be expended on moving it the first few millimetres. Once you've created even a tiny degree of motion, the task becomes rapidly easier-until suddenly it will be quite impossible for those same muscles to halt the movement.
The human brain does not operate in quite the same way; but the brain, once started, works awesomely fast. (Yes, even yours!) Indeed, one way to ignite your study-energy is to remind yourself that you are the proud possessor of the most powerful and sophisticated machine that has yet appeared on earth: the human brain. Since it is so much easier to start a task if you feel confident about it, I am going to dwell for a few minutes on some of the amazing properties of that small chunk of grey matter between your ears. I want to show that, no matter how dozy or stupid you may feel, your real capacity is staggering!