When you flex your muscles you are contracting them. When your muscle fibers gain tension through Actin and Myosin crossbridge cycling they may shorten due to the tension. This is called muscle contraction
Physical activity reduces stress because it helps get your brain moving and doing something other than the anxieties and stress. When your active you are more focused on the thing your doing rather than the stressor/s. It has also been proven that sitting and stressing makes it worse so to move your mind off it for a hit helps you to relax and also gives your brain time to think things out.
A.Showing Aggression because if u show arrgrisiveness then you will/would end up starting a fight which is a negative way of dealing with it. Hope it helps mate
3)by putting in effort and hard work
