Memory is like a muscle: you either use it or lose it. Consider this definitive guide a personal trainer for the brain, one with a huge assortment of entertaining and fast-acting memory-strengthening techniques. Use them to draw upon daily, when trying to find lost keys, recall anniversaries, or study for exams. Test your sharpness with fun instant assessments. Try intriguing short- and long-term memory tasks, such as remembering a series of long words and recalling landmarks on a map. Follow a monthlong plan of “do it in a day” exercises. In addition to invaluable “Tips and Tricks” boxes, there’s advice on boosting concentration, using mnemonics, and other forms of mental association.