Colouring
Colouring books are not always for children. Research has shown that colouring can be beneficial for young adults as it fosters creativity, improves mood and assists with meditation. Colouring has a positive effect on anxiety and stress - and above all it's fun!
There's a wide variety of books and sheets on the market aimed at young adults including: mandala, flower patterns, graffiti, geometric pattern, and etc.
http://www.huffingtonpost.com/2014/10/13/coloring-for-stress_n_5975832.html
http://shegetscreative.hubpages.com/hub/benefits-of-coloring-for-adults