The kids kind!!
I am a HUGE advocate for colouring in, whether you are 5 or 50 or anything in between or above, it is the best way to relax and de-stress! I used to work in a pretty stressy job dealing with benefits & would always have a colouring in book and a pack of pens out on my desk so i could colour in between calls. It kept me sane (ish) for the 4 and a bit years I worked there and would recommend it to anyone. Since Christmas I've given out 4 sets of books and pens and not one person has been disappointed. This year i gifted myself 2 new books & new pack of pens & find time each day (usually just before bed) to do a bit of scribbling!
You may think it's a bit bonkers, but give it a try...i assure you, you will love it!