Joseph Heller, author of Catch-22 and Portrait of An Artist as An Old Man, explained why he kept writing,

"I have nothing else to do. The phone isn't ringing much anymore with calls I don't want to receive. There are no more faxes coming in with requests for interviews I don't want to give, no invitations from people I don't want to see for parties I don't want to go to. Damn it, I miss those interruptions!. . . Writing is about the only way I can define myself."

~ Joseph Heller (1923 - 1999) American satirical novelist.
Heller introduced a new phrase into the English language with "Catch-22." Simon & Schuster, 1961.

Source: Endangered Species, Writers Talk About Their Craft,Lawrence Grobel, Da Capo Press, 2001.