I would add to ta, zolof, internet shopping,netflixmarathons, audiobooks while walking, mindfulness practise, love the chocolate meditation by mark williams ..
http://franticworld.com/free-meditations-from-mindfulness/Spending time with friends doing funstuff, preferably active where you have to keep your mind focussed so you can't drift into thoughts.
I bought some lego buildings for 16+ which is like 3d puzzles except less boring. Mindfull lego-ing saved me
( now I don't know where to keep the buildings)
I read a lot of uk crime/ detective novels just all type of books that grip your mind and you want to know how it finishes, but you don't have to do a lot of thinking while reading.
Giving yourself "time off" of cancer is so important to keep going...
Oh, and I spend a lot of time surfing this forum, looking at the fun topics
Making holiday plans for after treatment, gardening especially getting rid of unwanted plants agressively
Annemiek