The beauty of Robert Thayer's mood research is that it is so firmly grounded by the documented experience of thousands of people. He can say with authority that the best ways to improve mood are to take a walk or talk to a friend or meditate or pray. Meanwhile, other researchers, such as James Rippe, M.D., at the University of Massachusetts, have expanded on that work to test combinations: Are walking meditation, prayer-walking, and mindful exercises such as Tai Chi more effective at boosting energy and reducing tension than walking alone? The answer, not surprisingly, is yes. Combining prayer or mindfulness with walking turns out be a "double dip" of happiness. So perhaps it's not surprising that men like Gandhi and Christ spent so much time walking either in conversation with disciples or in meditation and prayer.

Which brings us back to the question of the whereabouts of the soul. Dr. Anne Foerst, the theologian who helps build humanoid robots like Kismet at MIT's Artificial Intelligence lab (see www.spiritualityhealth.com/path/ai.html) says that the Greek idea of a disembodied soul makes no sense at all, at least in terms of trying to build a human from scratch.

Why? Our intelligence, our sense of self, she explains, is "embodied." In other words, our sense of self is not just in our brains but is distributed from head to toe. Moreover, that embodied intelligence is "embedded" in the world. That's a complex notion, but quite simply it means that our memories, for example, are partially stored outside ourselves -- in our surroundings, our friends, our scrapbooks. One of the many lessons of modern "Embodied AI" is that we develop only in relationship to our surroundings and to other people -- and that our lives are much more "virtual" than we believe. Despite what we may think, the lesson of the latest robots is that mind, body, and spirit cannot be separated.

Which brings us again to the simple keys to a soulful life (and a good mood): Walk with friends and walk with God.

Wondering how to start? While books have been written on the technique of prayer walking, all you really need to know to do it is to choose your own mantra or prayer -- peace, shalom, Not my will, but Thine -- and repeat it rhythmically as you walk, say, every time your left foot hits the ground. You can't do it wrong.

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