system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What promotes a better immune system, being sick and recovering (with or without medication) frequently or avoiding being sick as much as possible?
gpt
One important note here is that being "sick" and preparing your immune system are not the same thing.

Someone working outdoors, getting occasional scrapes and breathing in pollen and detritus is giving his immune system a workout (to oversimplify) and someone trapping themselves in a sterile climate controlled room is not.

The adventurous person is more likely to encounter pathogens, and one or more of them might be of a dangerous enough variety that they get sick. The person hiding from germs isn't as likely to encounter pathogens, but could get very sick from pathogens that the adventurous person's body would fight off before they noticed any symptoms.

Their is no "what is better" because life is too dynamic and circumstantial.