Look at your diet and your workout program. Could be overtraining, lack of nutrition, or a plethora of other things. Post a little more info as to what you normally do and what it is you might consider as tired. Make sure your getting plenty of sleep(8hrs or so), and that your workouts are not over taxing your CNS. Lack of vitality can be from several different things. If you feel like it's something your missing in your diet, check out Poseidon and read some reviews about it. Could be just what your looking for.