Waking Up is what came to mind for me as well when I read the OP.

I also had the same questions as OP before I started. Even on HN, when meditation would come up, people would mention the spiritual/eastern roots (often to the tune of "ugh westerners suck they don't even get it") which was always a let down to me: if mindfulness is useful by itself, then surely it doesn't need to be encumbered with or require buy-in to all this other bullshit.

Thankfully, mindful meditation is indeed useful stand-alone.