We can't predict the future, yet we do it all the time. We organize projects, events, days, weeks, and years. We plan to buy a home, build a career, travel, get married, raise children, teach a class, retire, or get in shape. Our ability to model the world as it is and might be is a gift, but mental time travel is also really hard. Fortunately, since planning is a skill, everyone from playful improviser to rigorous planner can greatly improve, if...