The themes of adult coloring books are usually intricate and centered more around adult images, not your childhood counterparts that included bunnies, super heroes, and farm animals. You would expect to see geometric patterns, psychedelic patterns reminiscent of doodle art type pages, fantasy images including angels, dragons, goddesses and mermaids, and ancient designs of religious and spiritual nature.
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.
The repetitive, low-stress, and "no brainer" act of color lends itself to relaxation. The calming effects not only helps to reduce stress levels, but also can help to bring you back to your youth. The awesome part is that anyone can do it will no skill set required! Grab a crayon and you are good to go. You can make it even more enjoyable and have your kids or grandkids color with you. Depending on the age of the young ones they may be interested in the adult coloring books, others still wanting to color a cow, astronaut, or pretty flower arrangement.