Your energy levels will depend on several factors, including genetics, nutrition, sleep habits, and emotional stress. Some of these you have no control over But there is one VERY important factor that you do have control over and that is your ability to take part in physical exercise.

Need a source of vast power and energy?

Look no further than your gym.

The link between physical fitness and energy is so strong, that doctors have lately been prescribing exercise as treatment for chronic fatigue, depression, seasonal affective disorder (SAD), and insomnia, for instance.

If sufferers of the most stubborn kind of fatigue can be energized with exercise, imagine what can do for those of us who experience ordinary, every-day fatigue.

* Feel Great At Mid-Afternoon *

Your brain thrives on oxygen. Blood transports oxygen to the brain, so the greater blood flow to the brain, the greater the oxygen supply the brain has. As you increase your heartbeat with a vigorous workout, more blood surges through the brain, more oxygen gets absorbed by your brain cells, and you feel more mentally alert and energetic.

Experts point out another long-term cause-and-effect relationship between exercise and blood flow to the brain: as you continue exercising, the number of capillaries (small blood vessels between your arteries and veins) throughout your body will grow. More blood flow through your "pipes" means more oxygen will be supplied where you need it.

Regular exercise also keeps the pipes clear and circulation healthy by preventing atherosclerosis (buildup of plaque). Regular exercise can actually REVERSE atherosclerosis when combined with a healthy nutrition plan. When you have atherosclerosis in check, your brain is virtually guaranteed for the rest of your life.

Blood also carries glucose, the simple sugar that's the primary fuel source for your entire nervous system of which the brain is the command center. Glucose's production starts the metabolism of carbohydrates. Various enzymes, plus your body's ability to use glucose to produce ATP, the more important energy chemical in the body, control this production. When you exercise, you increase the level of those enzymes and their activity.

In other words, when you exercise regularly, you boost your enzymes, resulting in more glucose, and your body is more efficient in using the glucose. You get a larger supply of ATP, which helps fight off the mid-afternoon energy drop-off.

* Increase Metabolism *

It's no secret that strength trainers are firmer and stronger than sedentary folks. How could it be otherwise?

Resistance exercise builds muscle, pure and simple. The more muscle you have, the higher your metabolism, and the more calories you burn even at rest.

So why does "strong and toned" equate to more energy?

For starters, heavy people have to lug around more weight all day long. When the overweight climbs a flight of stairs, do yard work, or even just carrying the garbage can to the curb, they're also carrying that excess weight, making almost everything they do more exhausting.

Better-conditioned muscles make every task that much easier, regardless of body weight. When you exercise, your ability to use muscle fibers is increased. So you require less effort to perform any physical task.

A strong body also has a stronger immune system. Being sick drains us of energy, and exercise, by boosting immunity, staves off illness. Recent research has shed light on why the strong may get sick less often and recuperate faster when they do get sick: exercise increases the activity of natural killer cells in the bloodstream.

* Less Stress *

A great deal of research supports that weight lifting is one of the most effective means of battling depression and stress. One of the main fatiguing factors of depression and stress is lack of sleep. In a recent Stanford University study, formerly sedentary insomniacs who began to exercise fell asleep 15 minutes faster and were able to sleep an hour longer than they had before becoming active.

* Boost Brain Fitness *

To this point, we've been talking about the benefit of exercise on mental energy. But is it possible that being in shape might translate to even greater mental benefits, such as increased intelligence, creativity, memory, or reasoning ability? It's very possible.

Studies show that both factors of mental stimulation and exercise were contributing to the increase of the brain's learning centers in different ways. Mental stimulation results in more synapses (the little gaps between brain nerve cells that enable them to communicate with one another), while exercise increases the number of capillaries in the cerebellum and cerebral cortex (two areas of the brain crucial to intelligence.)

* Take a Walk *

Medical research results could hardly be clearer: Taking a walk is one of the best ways to take charge of your health. A study in the Journal of the American Medical Association (February 11, 1998) showed that walking briskly for half an hour just six times a month cut the risk of premature death in men and women by 44 percent. A study in the New England Journal of Medicine (January 8, 1997) reported that men 61 to 81 years old sharply reduced their risk of death from all causes, including cancer and heart disease, by walking two miles a day. Other research has shown similar results for women.

Recent studies have concluded that moderate amounts of exercise - including walking, jogging or using a treadmill for one hour, four to five times a week - can turn back the aging clock 30 years for middle aged men.

Consistency is probably the most important part of your workout. The more committed you are to walking all or most days of the week, the healthier you'll be. Remember that short walks are better then none at all. Health, like life, is a journey. All you have to do is take the first step.