Move around. When you feel your mind beginning to fade, stand up and take a short walk around your home or the neighborhood. The movement will get your oxygen flowing and consequently your energy level will be boosted.
Keep the temperature down. If you try to warm up with the heater, you are creating the perfect sleeping environment. Conversely, it will be difficult to fall asleep in a room in which your body temperature is slightly uncomfortable.
Drink plenty of water. When the human body is properly hydrated, blood circulation improves and energy levels increase.
Look away from the computer monitor. Allowing your eyes to stare at a monitor without a break can lead to further exhaustion and weariness. Take the occasional break from your hard work and look at something else for a few minutes.
Eat a nutritious snack. Resist the temptation to consume excessive amounts of caffeine, or snack on sugary treats. These less than healthy options may provide you with some short term energy, but will ultimately end in a worsened state of exhaustion. A healthy snack such as a banana or apple will provide you with vitamins and minerals. In addition, you will fill yourself with good carbohydrates that will help boost your energy level.