KEVIN ROSENBERG IS IN NO SHAPE TO BE GUIDING ME down a sloping, leaf-littered path on a crisp mid-October morning, toward a waterfall that has claimed several lives in the past two years. His hands are jammed into the pockets of a pair of loose-fit jeans. His right side is locked up, from the waist down. When he takes a step, it looks like his leg is fused to his hip. He's having one of the lower back pain (likely sciatica) attacks that have plagued him intermittently since he first injured himself lifting boxes at 19. We're 60 miles from New York City, at the tail end of a several-hour day during which we've been driving through the Catskills instead of hiking them. This quick hike-to-the-deadlywaterfall is a last ditch for Rosenberg to show me what could have been. I flew to New York three days ago, hoping to join him and his clients on a two-night backpacking trip. Unstable weather apparently scared off prospective clients, so the trip was cancelled. Then Rosenberg came up