Feeling tired at times is a normal part of being human. However, if you are constantly feeling tired then you should see your doctor as you gradually notice some alarming body symptoms. In the meanwhile, there are few things you can do to alleviate the problem:

Eat small meals
Start a new routine of having healthy snacks gradually throughout the day and regular balanced meals.
This is so much better than having just a huge meal and eating junk food every now and again.
Foods rich in fibre make you feel full for longer and carbs fuel the body with energy to be used efficiently by the muscles.

If you introduce exercise in your lifestyle carefully you will notice an increased level of energy and uplifting spirit.
Start small and then build it up step by step until you reach the recommended 2h.30m of moderate intensity aerobic exercise. You could try swimming, cycling, power walking.
Just remember to start in small steps towards a more consistent and stronger workout.

Lose weight
Carrying excess weight in your body actually drains your energy levels and overloads the cardiac and respiratory systems.
The worst danger lies in accumulating fat around the middle. You do need to watch out as that flabby waist means you certainly have layers of fat installed inside your internal organs.
Try eating a balanced diet and exercise regularly to achieve and maintain a healthy body weight.

Have enough sleep
Since the beginning of recession a lot of people started having sleep problems and still have no idea how that sleep deprivation affects their daily performance, internal balance and overall harmony.
Although people’s habits and lifestyle vary, the average to aim at should be 8hrs sleep per night.
The secret to achieve this also lies in a bit of self discipline: go to bed and wake up everyday at the same hour everyday, introduce the habit of having a soothing bath and other relaxing activities before bed time.