Don't fight fatigue. Rest when you need it. Try to take small naps during the day. Try to keep to a regular daily routine that is reasonable. Start an exercise program.
Exercise can significantly help to relieve fatigue.
Start slow at first and work up to a program you can live with. Drink lots of water during the day. Eat a well balanced diet with frequent, small meals. Avoid caffeine in the evening Get a handle on the stresses in your life. Take time to put them in perspective.