If you are like me and only have a shower you can get bath bombs especially made for the shower. Otherwise a bath bomb.
I find that joining postcrossing very good and a distraction. If you dont know what postcrossing is it's a postcard exchange website. I tend to write the same thing though for everyone.
The other thing that sprung to mind is adult colouring books. You can get them on a variety of topics eg zen/Harry Potter.
If you're artistic then painting can be good. If you like the idea of painting but not up to doing a painting from scratch then an painting by numbers kit is good.
Other than that I have thought of is putting a face mask on and nail varnish.