"A price drop in a good stock is only a tragedy if you sell at that price and never buy more. To me, a price drop is an opportunity to load up on bargains from among your worst performers and your laggards that show promise. If you can't convince yourself "When I'm down 25 percent, I'm a buyer" and banish forever the fatal thought "When I'm down 25 percent, I'm a seller," then you'll never make a decent profit in stocks."