There are two types of situation that work for me. So far as creative thinking is concerned, give me a fairly mindless job like lawn mowing. I go into a stream-of-conciousness mode and come out with a song lyric or art concept; occasionally one that is actually worth following up on.

At other times I need to be "triggered". That may just mean being engaged in intelligent, challanging conversation, or it may mean hearing some supposed leader or expert address something that I hadn't really thought through, having one of those "that's just wrong" reactions, and being somewhat obsessed until I can clarify my own reaction and my own position.