Well, apparently they were back then and still are today for people of all ages. People are making the adult coloring books bestsellers on Amazon! At the time of this writing, eight of the top twenty books on the bestsellers list, are coloring books for adults. There must be something behind this recent growth in interest.
Coloring in pages that are specific for coloring. I have found a few websites that have pages to color that are downloadable. You can also try a resource store for teachers. These specific pages for coloring are pictures or drawings of a variety of design that you alone enjoy. You can make your own coloring book with these pages. After coloring the designs you can write your own narrative about how you feel. Write how the design itself and the colors you used relieved your stress. You can even write a short story about the design if you like, this is your project and it is for your eyes only.