Not Exercising
This is one of the biggest health issues in the world. Not only does this increase obesity, heart disease and a multitude of conditions but it greatly affects the immune system. Toxins build up in the body and decrease immunity. All the other diseases also, of course, impact the immune system and its strength.
Fear
When you get scared or catch a fright your body goes into a “fight or flight” response. This happens more often than we think and can be stimulated by multiple things, sometimes in anxious people extremely often. This wears and tears on the body and the immune system as the shockwave adjusts many bodily functions.