"Reasons to Be Cheerful" is a science-fiction short story by Australian writer Greg Egan,[1] first published in Interzone 118 in April of 1997.
After also losing balance when walking, a medulloblastoma is discovered in his brain causing higher levels of Leu-enkephalin, which binds to the same receptors as morphine or heroin and hence is the reason for his happiness.
Mark returns to Sydney and takes a job in a bookstore, in which he can use spare time to read its books, and begins to date Julia, who comes by there often.
In the latter he considers it to be his favorite short story as it "felt [....] like a jigsaw puzzle that couldn’t have been put together any other way.“ He added that "more than ten years later", he is "still happy with every word", which "doesn’t happen often.
"[6] Salik Shah, writing in the Reactor Magazine, compared the protagonist with Frannie Goldsmith (Fran) from Stephen King's The Stand and remarks, that he doesn't think she "would have said yes to such a medical intervention."