Water is important. It makes up 60 percent of your total body weight and carries out many essential functions in your body.
When you exercise, you lose water through your sweat. So you need to put some back in. All straightforward so far.
I’d be the first to admit though that I don’t understand how much I should be drinking when exercising. It seems to be a delicate balance between avoiding the need to take a wee every few minutes and dying of thirst. And it’s one I never seem to quite get right.