A man will be imprisoned in a room with a door that's unlocked and opens inwards; as long as it does not occur to him to pull rather than push.
I used to look at this and believe that it meant all my problems were almost imaginary, a matter of my state of mind. I think its closer to the truth to say that a man will be imprisoned in a room because he doesn't understand his surroundings.
I wouldn't presuppose that it is possible for someone to come out of the state of mind. Or you could take a page out of my mother's book, one should choose to be happy.