If you feel like you're always tired you just might have a vitamin or mineral deficiency such as low levels of iron, vitamin D or B12. The only way to be sure this is the cause of your fatigue is to get a blood test taken at your doctor's office. In the meantime you might want to consider taking a multivitamin and a vitamin D supplement daily.
Feeling down or depressed can cause fatigue. Research indicates people with depression may be four times more likely than non-depressed people to experience unexplained fatigue. 30 minutes or more of exercise a day three to five times a week is effective at treating mild to moderate depression. If that doesn't help, see a doctor.
If you are stressed, your adrenal glands may be working overtime and causing fatigue. If you're always stressed the adrenal glands can tire out and produce less adrenaline and cortisol. The result is a condition called adrenal fatigue. To give adrenal glands a chance to rest try meditating for at least five minutes a day.
What you're eating and drinking can also case fatigue. People who are perpetually dehydrated can also feel fatigued so be sure to get in your eight cups of fluids a day. Food sensitivities can also bring on fatigue. So, try to stay away from processed foods and consult a dietician.
If you've tried all of the above and you are still tired, talk to your doctor. You might have a hidden illness such as Fibromyalgia sleep apnea.