You should look at the number of cases vs the number of deaths in the UK this time last year vs now. Cases are high again - deaths aren't. https://www.worldometers.info/coronavirus/country/uk/
I'm not sure at what point you concluded that the experts said don't worry about diet and exercise, because I'm pretty sure they didn't.
Lots of people have one comorbidity or another, so 'this would be over' is arguable. Could they have pushed for it harder? Sure, but given that people pushed back on everything else, I'm unsure how that would have gone. https://www.health.harvard.edu/blog/does-exercise-help-protect-against-severe-covid-19-202106092475
I think we'd be in a lot better position if people had social distracted and worn masks in earnest since no virus can survive long without being transmitted. Instead, we had some doing it and some not which was about as effective as fixing most of the holes in a boat. The people who don't do their homework always complain the loudest that the teacher is unfair.
But we can't know what might have been in either case.
Pfizer advertising - welcome to the free market. They only started that on August though.
I'd rather be - sure, but it's isn't a game of would you rather. I'll take exercise, a healthy weight, and vaccinated, thanks.