Physical energy is the fundamental source of fuel, even if your work is sedentary. Not only does it lie at the heart of vitality and alertness – it also affects your ability to manage your emotions, sustain concentration, and think creatively.

The size of your energy supply depends on five things:

1. The pattern of your breathing.
2. The foods you eat, and when you eat them.
3. The quantity and quality of your sleep.
4. The degree to which you get periodic recovery during the day.
5. The level of your fitness.

Breathing

Few of us ever think about our breathing. Air becomes precious only in those rare times when we can’t get enough, such as when we’re choking on some food.

But the breath is a powerful tool for self-regulation. It helps both summon energy and to relax deeply. Here’s an effective way to breathe:

Breathe in for a count of three, and breathe out for a count of six.

Not only does this method of deep breathing quiet your body and mind – it’s also a source of energy and focus.

Eating

The second critical source of physical energy comes from the food you eat. It’s hard to function effectively on an empty stomach. On the other hand, overeating leads to obesity. But by eating better, you’ll have the steady source of energy needed to sustain high performance.

When it comes to meals, breakfast is crucial. After eight hours without eating, your blood glucose levels are low. Eating when you wake up jumpstarts your metabolism.

It’s just as important to eat foods that are low on the glycemic index. The lowest-glycemic foods provide the highest octane and longest lasting source of energy.

Here are some foods that are the lowest on the glycemic index:

• Almonds
• Apples
• Beans
• Cabbage
• Cherries
• Chicken
• Eggs
• Grapefruit
• Green vegetables
• Oranges
• Peanuts
• Pears
• Plums
• Prunes
• Soy milk
• Tomatoes

How often you eat, as well as how much you eat, also influences your ability to sustain high performance. Eating five to six low-calorie, highly nutritious meals a day will ensure a steady supply of energy.

During each meal, eat only as much as you need to feel satisfied, driving your energy for the next two to three hours. Satisfaction is the point where you’re neither hungry nor stuffed, and you can’t feel the food in your stomach. Again, this lasts for two to three hours, and is the ideal performance state.

Sleeping

Other than eating and breathing, sleeping is the most important source of recovery. Your cardiovascular capacity and mental performance decline as sleep debt increases.

Sleep needs vary, but the broad consensus is that you need seven to eight hours of sleep to function optimally. During periods of deep sleep, the greatest number of growth hormones are released, and muscles that have been stressed during the day have the chance to regenerate. You heal and grow the most during the deepest periods of recovery.

Recovery Breaks

The shifts of energy that you experience are tied to ultradian rhythms, which regulate physiological markers of alertness at 90- to 120-minute intervals. Somewhere around 3:00 to 4:00 pm, you reach the lowest phase of both your ultradian and circadian rhythms.

This is the time when you feel the highest level of fatigue. By getting real recovery breaks – preferably sometime in the afternoon – you’ll sustain a high level of energy well into the evening.

Fitness

Both strength and cardiovascular training have a powerful impact on your energy level and performance. Though conventional wisdom says that the best way to build fitness is through sustained aerobic training, interval training is actually preferable to continuous exercise.

In a study conducted by Harvard and Columbia, researchers found that short doses of intense aerobic activity – each one sixty seconds or less – followed by complete recovery, had a positive impact on participants. After eight weeks, the subjects improved their cardiovascular fitness, mood, as well as strengthened their immune systems.

Strength training is just as important as cardiovascular training, because loss of physical strength is connected with signs of aging and reduced energy capacity. The most basic workout is to exercise each of the six major body parts – shoulders, back, chest, biceps, triceps, and legs – by doing a single set of eight to twelve repetitions for each body part at an appropriate weight.

For more tips on how to increase your supply of physical energy, check out The Power of Full Engagement by Jim Loehr and Tony Schwartz.