Why am I always tired? 22 medical reasons for feeling tired

Lack of water
Around 60% of your body is made up of water, so you need to constantly keep it topped up. Not drinking enough water during the day can lead to headaches, muscular problems, concentration, memory problems, and fatigue.Everyone is different, and working out how much water you need depends on many factors. But the average recommended amount for a man is around 3 liters per day, and a woman just over 2 liters.