It is the systematic use of exercises to promote bodily fitness and strength.
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.
Maintaining a healthy weight keeps your body healthier and more able to fight of diseases as all the blood cells are more active. The healthier that your weight is the more likely that your body will be able to fight off disease.
diseases that can be prevented
DIABETES (TYPE 2)
BLOOD PRESSURE (because of the unhealthy weight the red blood cells struggle to get round the body)
ASTHMA (problems with breathing as the weight can hold you back as you get tired and inhale and exhale slower )
It stands for ultra-violet