Non-fiction and play recommendations

I think I would like to read a bit more non-fiction than I do currently, and I have a couple of things on my to-read list, but not a lot. Most of what I have read recently has been about psychology or economics, but I'm keen to broaden my horizons (as well as reading more interesting stuff in those genres).

What are your favourite non-fiction books? What do you like about them? Are there any that you found life-changing?

I would also like to read more plays (which, outside of readthroughs, I almost never do), so the same questions apply.