I heard about this through a podcast interview with the author.
It was still not what I expected, but in a good way.
It is about how we deal with the limited amount of time we have on earth and about good or bad ways to deal with it.
A lot of it will sound familiar and he quotes a lot of authors who have written about related topics.

My quick summary would be:
- enjoy everything you do in the moment for what it is
- choose a few things to focus on
- don't worry about missing out on opportunities, you can't avoid it anyway
- just don't worry so much
- everybody is winging it

I think this book could have been a lot shorter, but probably because I am still optimizing for time and sometimes things just take as long as they take.