"You can't make headway without thinking about a problem for a long time, in collaboration with smart researchers from different fields, as well as reading a lot," says epidemiologist Caroline Buckee, one of CNN's 10 Thinkers for 2013. "But sometimes that hard work reaches fruition or comes together at a random time once you have let thoughts settle down."

http://edition.cnn.com/2013/10/23/tech/innovation/thinking-time/

For me it’s always in the shower.