People assume you sit in a room, looking pensive and writing great thoughts. But you mostly sit in a room looking panic-stricken and hoping they haven’t put a guard on the door yet.

Douglas Adams (1952-2001) English author, humorist, screenwriter
Interview (2001-04-05) by Brendan Buhler, “Man of the Galaxy,” Daily Nexus, University of California, Santa Barbara
    (Source)

Collected in The Salmon of Doubt, Part 3 "And Everything" (2002) [ed. Peter Guzzardi].