This question is quite interesting from my point of view. I have a rather good default state which, if necessary, can be reached through meditation. I don't need to be in the zone when I go out, since I know I'll get there if the following condition is met: I get engaged in a conversation with someone who gives something back, inspiring each other, pumping up our state together. The opposite is more common though, and makes my state drop back to default.
Another interesting epiphany I've had recently is that some people can't tolerate people who have fun. I don't know what kind of problems they have, but they will intentionally try to destroy your state. I'm not talking about asshole strangers, but coworkers of mine and such. People one would otherwise consider "normal".
So in general, my method to get in state is to hang out with the right people, and avoid all others.
