I got a tattoo over the weekend. Okay, it's only a spray-on tattoo, but it is the visual reminder of my weekend, of a night on the Santa Cruz Beach Boardwalk with my leadership students and over 700 other junior high school students. I have received comments, questions, and even a look from a stranger about the tattoo, most of which have required me to explain its origin. This tattoo is a symbol of my past, and these events show me that my decision to get one in the past has affected me in the present. The same is true for all our decisions. The choices we make in the past, whether public or private, influence our present perceptions, behavior, and dispositions. This is true not only for major life decisions-- a career path or spouse, for instance-- but even for the daily habits of thinking in which we actively and passively engage. For the major life choices, a person's choice of career is a more obvious example. In my own life, my decision to teach junior high school studen...