Most people, claims science writer Flora Davis, fit into one of these four basic energy categories:

Strollers: Little energy, chronically "wound down," able to quite happily sit and watch the grass grow.

You are a "stroller" if :

All your life you've found it difficult to keep up with other people.

In most situations you feel tired sooner than others.

People have told you they envy your serenity.

You sometimes wonder why other people become so aggravated over little things.

Sprinters: High-energy, fast-moving people with a formidable amount of drive. They forever over-schedule themselves, but, somehow, manage to get everything done.

You are a "sprinter" if :

People constantly tell you they can't keep up with you, or enviously wonder how you manage to do all that you do.

You often feel impatient because the rest of the world seems to be moving in slow motion.

You often feel that life is a downhill race, and the trick is not to lose control.

Sitting still is tough for you.

You think best on your feet.

Hurdlers: Plunge from very high to very low energy and then swing back up again.

You are a "hurdler" if :

During "up" periods you operate beyond your capacity and drive yourself to exhaustion -- afterwhich a period of lethargy sets in.

You sometines feel like you're in a car racing out of control.

You plunge from "highs" to "lows" so frequently, you have no idea what your real energy level is.

Trotters: Usually have an average energy level. Most people are trotters.

You are a "trotter" if:

You usually have a moderate amount of energy, but can recall times when you've had so much drive you don't know what to do with it, and other times when you could hardly get out of bed.

On an "energy scale" of 1 to 10, you'd rank yourself from 3 to 7.

You experience no flash of recognition as you read the descriptions of the other energy types.