One day, an expert in time management was speaking to a group of students and, to drive home a point, used an illustration those students will never forget. As he stood in front of the group of overachievers he said, "OK, time for a quiz." He pulled out a one-gallon, wide-mouth jar and set it on the table in front of him. He also produced about a dozen fist-sized rocks and carefully placed them, one at a time, into the jar. When the jar was filled to the top and no more rocks would fit inside...