Don't Worry, Be Happy: That popular 1980s song by vocalist Bobby McFerrin "is a pretty neat philosophy in four words," as he put it, about keeping one's head up when faced with the mundane problems of everyday life. Workers today could benefit, it seems, from its cheery if simplistic message. High unemployment, increased workloads, stagnant wages and 401(k) plans that more resemble piggy banks than nest eggs have many employees feeling dour. And bosses have taken note. A growing list of companies, including American Express (AXP) and KPMG, have jumped on the so-called "happiness coaching" bandwagon, hiring consultants to teach employees how to tackle problems effectively and feel better about work -- call it the corporate equivalent of saying "the glass is always half full."