If you are bothered by a lack of energy, no motivation, drowsiness, and a feeling of not caring about what happens, you may be one of countless Americans plagued by fatigue.

Why are so many of us so fatigued? There's no easy answer. Fatigue can stem from illness, poor sleep, stress, lack of exercise, overwork, medications, and depression. It can make us trudge through the day yet hit our beds wide awake.

Experts at the National Jewish Medical and Research Center (NJMRC) say fatigue comes partly from ignoring our limits in a society where sleep and relaxation are sometimes bad words. 

There's no magic pill. In fact, some drugs designed to fix causes of fatigue, including sleeping pills, can make matters worse in the long run. But simple lifestyle changes can help. Here are eight ideas:

Get a checkup

First, learn if you're sick and tired or just plain tired. How do you feel: As if you have the flu, as if your mind is in overdrive or as if you're depressed? Illness symptoms like loss of appetite, dizziness, muscle and joint aches, and cognition problems aren't normal, the NJMRC says. See your doctor.

Medicine can thwart some energy thieves, like hormone imbalances, allergies, and chronic infections. Some drugs, though, such as antihistamines and antidepressants, can cause drowsiness. Ask your doctor about changes.

Honor your sleep

You should reserve your bedroom for sleeping— not watching TV or reading, the NJMRC says. Do those things in another room. Keep in mind that stimulating your mind before sleep can keep you awake. So can exercising within a few hours of bedtime, drinking caffeine, or drinking alcohol. Do something quiet just before bed, such as taking a warm bath.

If you have trouble sleeping, don't toss and turn in bed. Get up and do something boring—folding laundry, for instance—to quiet your mind. How much sleep is normal? The National Sleep Foundation says adults get an average of seven hours each weeknight, but they might feel better with eight.

Tune your diet

"If you're not fueling your body correctly you may feel tired," says Althea Zanecosky, R.D., an American Dietetic Association spokeswoman. She says the USDA's My Pyramid website is a good starting place for learning how to balance protein, carbohydrate, and fat. A lack of vitamins and minerals can also make you feel tired. So can being overweight, which makes you use more energy for daily activities.

Don't expect one food to supercharge you. "Food is not a one-shot thing," says Zanecosky. Energy bars offer no miracle compounds, she adds, although they're convenient.

For a tune-up at home, try a nutritionally balanced combo of crackers, cheese, and fruit. On the run, an energy bar that mixes complex and simple carbohydrates may be better than a sugar-laden candy bar; complex carbs give a longer energy boost. Yet energy bars may yield a lot of fat and calories.

Drink that water

Drinking enough water and other liquids throughout the day can help keep your body functioning—and water also gives you energy.

Zanecosky explains that if your body doesn't get enough water, it has to work harder find water to use for metabolic processes such as turning food into energy. "Not having enough water is like not having enough oil in your car," she says.

Healthy drinks like juice can also fill your liquid needs, but watch the calories.

Eat smaller meals

Eat smaller meals throughout the day to provide a continual but not overwhelming energy source. Be sure to stay within your recommended number of daily calories. A big meal can make you feel sluggish, says Zanecosky. Eating less food more often may keep you (and your digestive tract) running more efficiently. To estimate what and how much you need to eat to balance your calorie intake and activity level, go to the My Pyramid website.

"By stretching your recommended number of calories over six meals you can raise your metabolic rate slightly so you can burn more calories," she says. You may also avoid the after-a-big-lunch energy drop, and your brain works best with constant fuel. Take care not to add calories to your total intake.

Take breathing breaks

When was the last time you stopped to take a long, full breath? The energizing effect of breathing breaks or other "moments of attention" can't be overemphasized, says Florence Meleo-Meyer, an instructor at the University of Massachusetts' Stress Reduction Program.

Ms. Meyer says conscious breathing helps renew the part of the nervous system responsible for restoring well-being. Weave breathing breaks through the day to maintain a more constant energy state.

Grab those sneakers

Exercise increases feel-good chemicals in the brain, eases stiffness tied to fatigue and helps muscles use energy more effectively, says the Centers for Disease Control and Prevention.

Before you launch an exercise program, talk with your doctor. If you're just starting out, begin slowly, perhaps with a walk around the block. Add time and distance gradually, taking care not to come home feeling too tired. 

The USDA Dietary Guidelines for Americans 2005 recommend aiming for 30 to 60 minutes of moderate-intensity exercise on most days of the week. Stretching exercises and weight training should be part of a weekly exercise regimen.

Live in the present

Here's how Ms. Meyer puts it: "If it takes 100 units of energy to run your life, and 35 of those are involved in thinking about the past, and 35 are involved in thinking about the future, then you don't have much left for the present moment."

Try what the Stress Reduction Program calls "attention strengthening." That's the act of paying attention to what needs to be done now. People think that if they slow down and pay attention they'll become less efficient. But you become more efficient, Ms. Meyer says, because you focus more clearly and revise priorities.

Take a breather

• Bring awareness to the sensation of your breath at your nostrils, chest or abdomen.

• Anchor your attention to each breath, noticing its rhythms.

• When your attention wanders, escort it back to the next breath.

• Take these breathing intervals when you stop at a traffic light, wash the dishes or take a walk. When you're anxious, sad or angry, focus on a few breaths as you feel the emotion.

• Take these breathing breaks to increase your focus and your energy in the present. Notice how you feel after you breathe.

Source: The Stress Reduction Program, University of Massachusetts