Monitoring or keeping track of your vital health signs is a simple habit that ultimately helps manage medical issues, point out potential health threats and avoid future health problems.
I don’t understand what you mean
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.
