As anyone setting out on a walk or bike ride knows, it's hard to empty your mind of worry and planning, analyzing and hurting, and that deadly armada of what-ifs. Your agitations seem to travel with you, and soon you conduct small theaters of the mind, in which you play various roles and rehearse dreaded or hoped-for conversations. But if you can, give yourself a mental vacation. Hold a board meeting of the psyche and agree to leave home all the worries, hurts and misgivings. Then you can set off to enjoy the sensations of being alive: the beauty of lights, the rustle of dry cornstalks, the birdcalls, the wind and sun on your face. Freed from the commotions of your mind, you can allow yourself to be the photographic plate on which the world etches itself.