You just don't drink enough water.
Let's face it, water is just not as exciting as all the other fizzy, sugary attractive alternatives out there.
The issue of course is you then suffer through the tiredness, dry lips, headaches & overeating associated with the lack of water, and that's no fun.
With your body being 65% water, it's something you just need to do more of.
But how you ask? Easy.