>You can see this in retirement, actually. There's real data showing mortality spikes in the years after people stop working. The structure of striving, even when it felt like a burden, was providing something that leisure alone can't replace. People who stop pursuing things often just... decline.

There's a popular cope answer to this "that wont be the case with me".

But unless you already have either a concrete footing in enjoying the small things in life just for themselves, or a greater mission that falls outside the line of work you'll retire from (like being an activist, or a hobbyist programmer or musician or something), then it absolutely will be the case.