It’s Keith Johnston Improv. It really helped me to become friends with my subconscious, imagination, destroy some assumptions about myself, reframe my view of children, of course laid a stone into my decision to have a child (like this year as opposed to “eventually” or some day as I started interacting with children after reading the book), showed me a cool hobby and a new way to express myself as an event organizer. I have like 240 highlights and notes in it, more than in any other book by far, it was really a book written just for me at that point in life, you know? It also has a bit of a twist towards the end. Highly recommend! I’m 33 if this provides some context I dunno :)
Oh there’s also a TED talk by the man, you can totally see he is something else by watching it and comparing to other TED talks. Makes more sense of you read the book though.