Remove the hair where the pads will be placed.
C is your answer for the question
So you can be ready an energized for the next day
It makes you more aware, especially with food. Often we don't know how much we eat until we write it all out (with calories, fat, protein, carbs, and whatnot). It's a way of self-monitoring. When you track your exercise it can be more of a motivator, to see your progress, what you're working out, your muscle development etc.
