All the grand tours are three weeks long. The typical build cycle in training is three weeks long. The life cycle of the cabbage worm is three weeks long. Most women recognize they are pregnant at three weeks. Three weeks, twenty-one days. How much can you improve your fitness in three weeks? If you gave yourself a three-week training camp, how many more watts would you produce at the end of it? How much fitter would you become? How much body fat would you lose? How much could your bike handling skills improve?