'Exercise' might marginally improve your chances of defeating COVID, but in order for it to have a material effect for most Americans it would take literally years of complete transformation of habits.
Furthermore, even that would not be remotely as beneficial as vaccines or social distancing, maybe not even masks.
Vaccines >>> Doing Cardio.
The reason the government probably does not talk heavily about 'eating well' as some type of 'response behaviour' to COVID, is because people will get the 'Joe Rogan' mentality, and believe that 'Good Nutrition, Hitting the Gym Hard, and Positive Mindset' will just 'Alpha' their way past COVID, when that's definitely not the case, i.e. people would get a vastly over inflated sense of what their likely trivial lifestyle changes will do.
And of course:
"yet they insist that relatively new novel vaccines have absolutely none" (side effects) - which is blatantly and offensively false. Literally every article about vaccines talks about their numerous direct side-effects that almost 80% of people exhibit. And literally 100% of vaccine recipients are warned directly of these, including symptoms of myocarditis, signs to look for and when to call a doctor.
Realistically, I can't argue with your point. It's like giving up. It's sad that many people won't take basic steps to help protect others (including themselves), but I guess that's a reality-check.
Those who are older, with multiple comorbidities, or are immune-compromised, listen-up: More than enough people don't a shit if anyone other than themselves lives or dies that you should probably just isolate yourselves from society indefinitely.
All the more reason to strongly urge people to get vaccinated. Clearly one can't count on neighbors, the community or broader society to take minimumal steps to help protect themselves and others.
So you're on your own, living life at your own risk. There is no "society", just you. Protect yourself and get the shots.
At this point, it's looking like 'mostly vaccinated' is the primary measure and beyond that we can live with it.
But there are important caveats in that 1) hospitalisations have been a problem and that if were didn't have vaccinations (which help a lot with serious cases) we'd be in a world of hurt so we need to keep up with the vaxxes (the antivirals are not a solution just yet) and 2) we need to accept there could be another wave that's worse than Omicron or Delta and that at least some measures have to be re-implemented.
But how can natural immunity prevent covid? Natural immunity appears after infection, it could not somehow magically appear before the infection.
Yes, if people are generally healthy (no diabetes, hypertension, high cholesterol and so on), they can fare better but it is not guaranteed. Yes, covid death toll in US is high, but it is not low also other countries with much better peoples general health condition.
We know that vaccines help tremendously to reduce serious illness. It is incredibly stupid to not use them.
I do not support vaccination against seasonal flu. You can do it and you probably should do it when you are old but the risk to NOT contact it for general population is at MINIMUM 75%, most likely close to 85-90%.
The risk to NOT contact covid is close to 0.