I don’t remember the conversation at all, but I do remember at one point in college telling a vegetarian friend of mine that I wasn’t into “all that healthy shit.”
Times have changed.
For me at that point, there was no draw to the healthy stuff. It wasn’t a defense mechanism—at least not one that I was aware of or can identify retrospectively—it just had no importance. There was no consequence to being unhealthy because I was 20, had always eaten like this, had nearly always been somewhat overweight, and it didn’t matter. No, I couldn’t run and wasn’t very flexible and on and on, but unless there was a call for those skills—and there wasn’t—it didn’t matter.
So not having connected consequences (short- or long-term) is one reason for the indifference.
Feeling powerless is another.
If a person has a strong external locus of control—they believe that things happen to them and there’s not much or anything they can do about it—then they’re not going to believe that they have responsibility for their health, and their reaction to an offer of information about health habits is most likely indifference.
The other underlying reason for a reaction like that would be for defense. A person knows on some level that what they’re doing is causing a result that they don’t like, but they have a roadblock—known or unknown—and aren’t fixing it. Their response is in defense of themselves.
Defense also comes into play in cases of insecurity. Sometimes insecure people latch on to every person or idea that comes through. But sometimes, they lash out at every person or idea that comes through. All ideas or plans are stupid or bad or dismissed on some detail or other.
This is at least part of why G.I. Joe was negligent. Maybe knowing is half the battle, but the other half—the doing—is much more difficult. Most somewhat-educated people know enough about health and wellness to keep themselves relatively fit. Doesn’t matter. In my classes and mentoring, teaching people what to do is not challenging. People following through? That’s the challenging part.