This is a good question, an important question for all of us. Hippocrates, the father of medicine, said, "Let your food be your medicine." Our bodies have evolved over many millenia to convert food to the chemicals needed for optimal functioning.There are many foods which boost energy levels. Watch the energy foods slide show posted below on the medicine.net site. Foods highlighted there include; apples; whole grains; nuts, especially almonds,brazil nuts, hazelnuts and cashes: lean meats like chicken and turkey; salmon and other omega-3 rich fish like sardines and mackerel; leafy greens like spinach and romaine lettuce; fiber, from sources like beans and vegetables; fresh produce; coffee, in moderation; tea, especially black and green; dark chocolate. Eat frequent small meals if energy is a problem for you. Also, start the day with a nutrient-dense breakfast, like a fruit smoothie mixed with a raw egg and a couple of slices of whole wheat toast with blueberry preserves. Drink lots of water too. This is so important to maintain energy levels. As far as vitamins are concerned, the B vitamins are the ones to pay closest attention to, especially vitamin B-12. Madonna swears by her vitamin B-12 shots, and medical science too recognizes the importance of this vitamin.Finally, consistent exercise will help you. Try to find something you enjoy and stick with it, something that uses all the muscles of your body rhythmically, like swimming, cross-country skiing or aerobic dancing.I hope this helps. Vince Lombardi once said, "Fatigue makes cowards of us all." Yet, when we have enough energy, it seems we can do virtually anything.