Eating well and exercise helps you recover from virtually everything. Keeping your machine in good nick is bound to lessen symptoms and speed up recovery. It's not a substitute for medical treatment, but by golly, it helps.

If people were getting vaccinated as soon as they could, in the US, for many people the circulating variants were different by the time you needed to get your fourth booster. It became more clear that we needed a bivalent booster, but it wasn't quite out yet.

My guess is that it wasn't that it wasn't effective, just less effective than an updated one would be.

Eating well and exercising protects your heart. COVID causes a lot of clotting. It might just be that people with healthy hearts are better able to handle the stress on the body than people whose hearts are already stressed.

You probably did, that is an insidious example of false news. Among reputable immunologists, that viewpoint is scoffed at. In no way would that ever be true, just more alt right nonsense and yes I know a credentialed scientist wrote that article but if you don’t think the culture wars the republicans are waging do not pay off scientists to manufacture fake results to help their platform then you are highly naive.