Berkshire, New York: Imagine that you could predict now much time you had left on Earth. Wouldn't you alter your lifestyle and habits to fulfill that prediction, so that you could optimize the quality of your days? David Kendrick of Berkshire thinks you would. That's why he recently patented a watch that runs in reverse chronological order and digitally indicates the number of years, months, days, hours, minutes -- and even seconds -- left before the wearer dies. A self-confessed "hippy type" who lives in a cabin in the woods and earns his living chopping firewood, Kendrick got the idea for his watch when his father-in- law was dying of emphysema. "He told us all the things he wished he'd done in his life that he'd never found time for," says Kendrick. Instructions and an actuarial table will help wearers program their watch with up to 50 lifestyle variables, including age, sex, race, heredity, diet, stress and exercise levels, and country versus city living. "If you eat right and exercise," says Kendrick, "the watch will reflect that. I want people to ask themselves, 'Is my lifestyle really worth it?' People don't realize how much damage they do to themselves," he says, "until it's too late." But what happens if the user dies before the watch indicates time up? "I guess I'll have to think about getting good insurance and lawyers," says Kendrick. "If someone lives longer than the watch predicts, however, we'll be glad to give them their money back. Or maybe they'll just be happy to have beat the system."