The key to gaining more energy, says author Flora Davis, is the elementary physics law: A body at rest remains at rest unless acted upon.

"To get energy," she says, "you must spend energy.

"When you're feeling anxious or depressed, don't just sit there -- do something. Take a walk, shovel snow, fly a kite. Use your physical energy to get your mental and emotional drive going again."

Among her other suggestions for combating an energy crisis:

1. Avoid getting more sleep than your body needs. It can throw off your circadian rhythms and be an energy drain.

2. Design your own energizing retreat. Incorporate things you enjoy and colors you find refreshing.

3. Work in natural sunlight as much as possible, especially during winter doldrums.

4. Make allowances, if you can, for the weather. Expect to feel a bit sluggish when the barometer is low or falling, or on the first few very cold or very hot days of a new season.

5. Take 15 minutes to imagine yourself doing something you truly enjoy. Focus on details: the way things sound, smell, taste.

6. Work on improving unhappy situations. They may be blocking your energy.

7. Discover your daily peak hours. Schedule yourself according to your prime time.

8. Try high-protein breakfasts and high-carbohydrate suppers. Some people say this provides an energy lift.

9. Learn what foods have "magic" powers for you. Use them when you need an energy boost.

10.Keep a week-long record of things that give you a lift. Walking, talking to a friend, reading the comics? Use these "energy turnons" more often.

11. Avoid using up energy on daily hassles. Instead of fuming when you're stuck in traffic or waiting for a late bus, try meditating.

12.Focus on one thing at a time. Concentration can energize.

13. See a doctor if you feel chronically sluggish and tired.