First of all, the middle sentence there is obviously laughable hyperbole. There is no metric by which one could claim that we are less healthy now than we've ever been. US life expectancy now is at least a decade longer than it was after WW2, and more than three decades longer than it was in the Reconstruction era. We may have a bigger obesity problem than we used to, but overall health is far superior than it used to be, in basically every way you want to measure it.
Second of all, it is absolutely right that poor diet and poor exercise are the main culprits in our unhealthiness, but those things are very difficult to fix because they are subject to personal choice. The government can do its best to keep particularly unhealthy things out of our food - and already does a lot of that! - but you can't stop people from choosing cheaper, calorie-dense carbs over fresh fruit and vegetables and lean meats (which tend to be more expensive).Rest assured RFK's desire to remove niche food additives will do absolutely nothing to make us healthier on the whole; contrary to what many gullible people believe, there is not some "poison" being added to our food to make us unhealthy (unless you want to count sugar and sodium, both of which are harmful in the amounts in which we consume them, which is not what RFK has been talking about).
As for exercise, you do what you can to promote healthy choices - make cities more walkable, tax gasoline and disincentivize automobile use, build parks and greenways and trails and lots of free, easily accessible spaces. But you can't force people to use those things. And, of course, that all costs tax money.
