It means that you know your immune system was able to take on the virus with only slight symptoms.
So you assume a person who PROBABLY has a healthy functional immune system will recognize this virus quickly after being infected, and not undergo a bad response.
You are also assuming that a person with a healthy immune system does not get a large viral load all at once. Because this could be critical. And this virus definitely can put out very large loads in some people.
I consider myself in very good shape. Hardly ever get sick from viruses (just minor head colds I think, and zero colds since the mask wearing and vaccinations started which is a lesson in itself for me. I will wear a mask in every airport and plane I am on from now on as this correlated with getting a head cold for me) I am still staying away from situations that from our models of how this virus is transmitted, would leave me vulnerable.
eg. There is no fkn way I am getting in a car or bus and driving for hours with people who might be ill. No fkn way. If you do, good luck. My cousin already had a work crew who drove back and forth from work every day with each other. 1 guy got it, they all got it and my cousin lost 4 young workers (20s) for about a week and a half. CC might be acquainted with this. Its not healthy for the people or business.
To me, this is just common sense based on what we now know about the virus.